All Common Core: 4th Grade English Language Arts Resources
Example Questions
Example Question #13 : Integration Of Knowledge And Ideas
Adapted from The Ants and the Grasshopper by Aesop (620-560 BCE)
One bright day in late autumn, a family of Ants was bustling about in the warm sunshine, drying out the grain they had stored up during the summer, when a starving Grasshopper, his fiddle under his arm, came up and humbly begged for a bite to eat.
"What!" cried the Ants in surprise, "haven't you stored anything away for the winter? What in the world were you doing all last summer?"
"I didn't have time to store up any food," whined the Grasshopper; "I was so busy making music that before I knew it, the summer was gone."
The Ants shrugged their shoulders in disgust.
"Making music, were you?" they cried. "Very well; now dance!" And they turned their backs on the Grasshopper and went on with their work.
Adapted from Aesop’s The Lion and the Mouse (620-560 BCE)
A Lion lay asleep in the forest, his great head resting on his paws. A timid little Mouse came upon him unexpectedly, and in her fright and haste to get away, ran across Lion's nose. Roused from his nap, the Lion laid his huge paw angrily on the tiny creature to kill her.
"Spare me!" begged the poor Mouse. "Please let me go, and someday I will surely repay you."
The Lion was much amused to think that a Mouse could ever help him. But he was generous and finally let the Mouse go.
Some days later, while stalking his prey in the forest, the Lion was caught in the toils of a hunter's net. Unable to free himself, he filled the forest with his angry roaring. The Mouse knew the voice and quickly found the Lion struggling in the net. Running to one of the great ropes that bound him, she gnawed it until it parted, and soon the Lion was free.
"You laughed when I said I would repay you," said the Mouse. "Now, you see that even a Mouse can help a Lion."
How are the ants in the first story and Mouse in the second story similar to each other?
The ants and Mouse are nothing alike and there are no similarities.
The ants and Mouse are both selfish creatures who refuse to assist anyone else.
The ants and Mouse both encounter trouble and need someone to help them.
The ants and Mouse are both small creatures who have the chance to help someone bigger than themselves.
The ants and Mouse are both small creatures who have the chance to help someone bigger than themselves.
The ants have an opportunity to assist the Grasshopper, who is without food, and the Mouse saves the Lion from the hunter’s trap. They are both smaller creatures who help others.
Example Question #14 : Integration Of Knowledge And Ideas
Adapted from The Ants and the Grasshopper by Aesop (620-560 BCE)
One bright day in late autumn, a family of Ants was bustling about in the warm sunshine, drying out the grain they had stored up during the summer, when a starving Grasshopper, his fiddle under his arm, came up and humbly begged for a bite to eat.
"What!" cried the Ants in surprise, "haven't you stored anything away for the winter? What in the world were you doing all last summer?"
"I didn't have time to store up any food," whined the Grasshopper; "I was so busy making music that before I knew it, the summer was gone."
The Ants shrugged their shoulders in disgust.
"Making music, were you?" they cried. "Very well; now dance!" And they turned their backs on the Grasshopper and went on with their work.
Adapted from Aesop’s The Lion and the Mouse (620-560 BCE)
A Lion lay asleep in the forest, his great head resting on his paws. A timid little Mouse came upon him unexpectedly, and in her fright and haste to get away, ran across Lion's nose. Roused from his nap, the Lion laid his huge paw angrily on the tiny creature to kill her.
"Spare me!" begged the poor Mouse. "Please let me go, and someday I will surely repay you."
The Lion was much amused to think that a Mouse could ever help him. But he was generous and finally let the Mouse go.
Some days later, while stalking his prey in the forest, the Lion was caught in the toils of a hunter's net. Unable to free himself, he filled the forest with his angry roaring. The Mouse knew the voice and quickly found the Lion struggling in the net. Running to one of the great ropes that bound him, she gnawed it until it parted, and soon the Lion was free.
"You laughed when I said I would repay you," said the Mouse. "Now, you see that even a Mouse can help a Lion."
How do the ants and Mouse react differently from each other when given a chance to help someone in need?
The ants decide to play a trick on the Grasshopper to teach him a lesson while the Mouse decides he will not play a trick on the Lion.
The ants do not get a chance to help someone in need, so their actions cannot be compared.
The ants help the Grasshopper when he needs food, and the Mouse leaves the Lion in the trap.
The ants do not help the Grasshopper and leave him to fend for himself while the Mouse repays the favor and saves the Lion.
The ants do not help the Grasshopper and leave him to fend for himself while the Mouse repays the favor and saves the Lion.
The ants decide that they will not help the Grasshopper because he has wasted his time instead of collecting food, whereas Mouse is repaying a favor to Lion and saves him. The creatures behave differently when faced with the opportunity of helping someone else.
Example Question #12 : Compare And Contrast Texts
Adapted from Aesop’s Belling the Cat (620-560 BCE)
The Mice once called a meeting to decide on a plan to free themselves of their enemy, the Cat. At least they wished to find some way of knowing when she was coming, so they might have time to run away. Indeed, something had to be done, for they lived in such constant fear of her claws that they hardly dared stir from their dens by night or day.
Many plans were discussed, but none of them was thought good enough. At last, a very young Mouse got up and said: "I have a plan that seems very simple, but I know it will be successful.
All we have to do is to hang a bell about the Cat's neck. When we hear the bell ringing, we will know immediately that our enemy is coming."
All the Mice were much surprised that they had not thought of such a plan before. But in the midst of the rejoicing over their good fortune, an old Mouse arose and said:
"I will say that the plan of young Mouse is very good. But let me ask one question: Who will bell the Cat?"
Adapted from Aesop’s The Crow and the Pitcher (620-560 BCE)
In a spell of dry weather, when the Birds could find very little to drink, a thirsty Crow found a pitcher with a little water in it. But the pitcher was high and had a narrow neck, and no matter how he tried, the Crow could not reach the water. The poor thing felt as if he must die of thirst.
Then an idea came to him. Picking up some small pebbles, he dropped them into the pitcher one by one. With each pebble, the water rose a little higher until at last, it was near enough so he could drink.
How are these two passages similar?
The mice and the crow are both faced with a challenge and fail.
The main characters of both stories have to come up with a plan to solve a problem.
Both passages are non-fiction texts with informative text structures.
None of the answer choices are correct.
The main characters of both stories have to come up with a plan to solve a problem.
Both of these stories are fables that are meant to teach a lesson or moral. The main characters in both stories have a problem that they must solve, and they plan first. This is characteristic of many fables.
Example Question #16 : Integration Of Knowledge And Ideas
Adapted from The Ants and the Grasshopper by Aesop (620-560 BCE)
One bright day in late autumn, a family of Ants was bustling about in the warm sunshine, drying out the grain they had stored up during the summer, when a starving Grasshopper, his fiddle under his arm, came up and humbly begged for a bite to eat.
"What!" cried the Ants in surprise, "haven't you stored anything away for the winter? What in the world were you doing all last summer?"
"I didn't have time to store up any food," whined the Grasshopper; "I was so busy making music that before I knew it, the summer was gone."
The Ants shrugged their shoulders in disgust.
"Making music, were you?" they cried. "Very well; now dance!" And they turned their backs on the Grasshopper and went on with their work.
Adapted from Aesop’s The Lion and the Mouse (620-560 BCE)
A Lion lay asleep in the forest, his great head resting on his paws. A timid little Mouse came upon him unexpectedly, and in her fright and haste to get away, ran across Lion's nose. Roused from his nap, the Lion laid his huge paw angrily on the tiny creature to kill her.
"Spare me!" begged the poor Mouse. "Please let me go, and someday I will surely repay you."
The Lion was much amused to think that a Mouse could ever help him. But he was generous and finally let the Mouse go.
Some days later, while stalking his prey in the forest, the Lion was caught in the toils of a hunter's net. Unable to free himself, he filled the forest with his angry roaring. The Mouse knew the voice and quickly found the Lion struggling in the net. Running to one of the great ropes that bound him, she gnawed it until it parted, and soon the Lion was free.
"You laughed when I said I would repay you," said the Mouse. "Now, you see that even a Mouse can help a Lion."
How does the author's purpose compare in these works?
The purpose of these works is to persuade the reader to be angry with Lion and Grasshopper.
The purpose of these works cannot be compared because they have totally different intentions for writing them.
The purpose of these works is to inform the readers about wild animals.
The purpose of these works is to share a lesson or moral that can be learned.
The purpose of these works is to share a lesson or moral that can be learned.
The purpose of these works is to share a lesson or moral that can be learned. These texts are meant to teach the reader a lesson that can be applied to their own lives in a meaningful way.
Example Question #13 : Compare And Contrast Texts
Adapted from Aesop’s Belling the Cat (620-560 BCE)
The Mice once called a meeting to decide on a plan to free themselves of their enemy, the Cat. At least they wished to find some way of knowing when she was coming, so they might have time to run away. Indeed, something had to be done, for they lived in such constant fear of her claws that they hardly dared stir from their dens by night or day.
Many plans were discussed, but none of them was thought good enough. At last, a very young Mouse got up and said: "I have a plan that seems very simple, but I know it will be successful.
All we have to do is to hang a bell about the Cat's neck. When we hear the bell ringing, we will know immediately that our enemy is coming."
All the Mice were much surprised that they had not thought of such a plan before. But in the midst of the rejoicing over their good fortune, an old Mouse arose and said:
"I will say that the plan of young Mouse is very good. But let me ask one question: Who will bell the Cat?"
Adapted from Aesop’s The Crow and the Pitcher (620-560 BCE)
In a spell of dry weather, when the Birds could find very little to drink, a thirsty Crow found a pitcher with a little water in it. But the pitcher was high and had a narrow neck, and no matter how he tried, the Crow could not reach the water. The poor thing felt as if he must die of thirst.
Then an idea came to him. Picking up some small pebbles, he dropped them into the pitcher one by one. With each pebble, the water rose a little higher until at last, it was near enough so he could drink.
The themes of these passages are different but the author chose a similar genre to tell the story.
Why would an author choose a fable to explore this theme instead of a different genre?
Fables are persuasive, so readers believe them.
Fables are informational text so they can teach the theme to readers.
Fables are characterized by their moral lessons.
These passages are not the same genre, so they cannot be compared.
Fables are characterized by their moral lessons.
Fables often use animals with human-like characteristics as the main characters to depict situations raiders can learn something from. Fables were passed down from generation to generation and retold to teach life lessons, so they are a genre frequently used to express a theme.
Example Question #1 : Using Evidence To Support A Point
Passage and table adapted from "Why Leaves Change Color" on "Northeastern Area," a website by the USDA Forest Service. <https://www.na.fs.fed.us/fhp/pubs/leaves/leaves.shtm>.
There are two main types of trees: coniferous trees and deciduous trees. Coniferous trees have small, needle-like leaves. They keep these leaves all year. One example of a coniferous tree is a pine tree, which has green needles during all seasons. In contrast, deciduous trees lose their leaves every autumn. Before these leaves drop and blow away, they change from green to colors like red, orange, yellow, and brown.
Have you ever wondered why deciduous leaves change color in the fall? This color change is caused by a chemical process in the cells of tree leaves.
Green leaves are green because they contain a green molecule, chlorophyll. This is a very important molecule in the natural world. Leaves use this molecule to turn carbon dioxide, sunlight, and water into sugar and oxygen in a process called “photosynthesis.” So, chlorophyll lets the plant store energy as sugar, which it can use as food. It also lets the plant provide food for anything that eats it, like a cow, a bird, or even a human!
So, what does chlorophyll, a green molecule, have to do with autumn leaf colors? Deciduous leaves also contain molecules of other colors, but the chlorophyll in the leaves covers them up in the summer. In the fall, deciduous trees stop making chlorophyll. Eventually there is no more chlorophyll in their leaves. The colors of the other molecules show through. The colors of these other molecules are the colors we see in autumn leaves. The next time you see colorful leaves in the fall, you’ll know more about the chemistry at work!
Consider the underlined statement, in which the author claims that chlorophyll "is a very important molecule in the natural world." In which of the following sentences does the author provide evidence supporting this statement?
"[Chlorophyll] also lets the plant provide food for anything that eats it, like a cow, a bird, or even a human!"
"Deciduous leaves also contain molecules of other colors, but the chlorophyll in the leaves covers them up in the summer."
"The next time you see colorful leaves in the fall, you’ll know more about the chemistry at work!"
"This color change is caused by a chemical process in the cells of tree leaves."
"[Chlorophyll] also lets the plant provide food for anything that eats it, like a cow, a bird, or even a human!"
To answer this question correctly, we need to figure out which of the answer choices provides information that helps convince readers that the author is correct when he or she claims that chlorophyll "is a very important molecule in the natural world." To support this statement, the correct answer needs to talk about the same concepts, so it needs to discuss chlorophyll and its importance in nature.
The answer choice "The next time you see colorful leaves in the fall, you’ll know more about the chemistry at work!" doesn't mention chlorophyll at all, so it's not correct. "This color change is caused by a chemical process in the cells of tree leaves" has something to do with chlorophyll even if it doesn't mention the molecule directly, but causing color changes in leaves doesn't seem to cause any other important changes in nature, so this isn't the best answer. Similarly, the answer choice "Deciduous leaves also contain molecules of other colors, but the chlorophyll in the leaves covers them up in the summer" describes how chlorophyll makes leaves appear green in the summer, but it doesn't tell us anything about why this is important in nature, so it's not the best answer either.
The best answer and the correct one is "[Chlorophyll] also lets the plant provide food for anything that eats it, like a cow, a bird, or even a human!" This talks about how chlorophyll plays an important role in nature by allowing plants to provide food for other living things. This sentence provides an example of how chlorophyll plays an important role in nature, so it provides evidence supporting the claim that chlorophyll plays an important role in nature.
Example Question #311 : Common Core: 4th Grade English Language Arts
Passage 2: Adapted from "Cyanocitta cristata: Blue Jay" in Life Histories of North American Birds, From the Parrots to the Grackles, with Special Reference to Their Breeding Habits and Eggs by Charles Bendire (1895)
The beauty of few of our local birds compares to that of the Blue Jay. One can’t help admiring them for their amusing and interesting traits. Even their best friends can’t say much in their favor, though. They destroy many of the eggs and young of our smaller birds. A friend of mine writes, “The smaller species of birds are utterly at [the Blue Jay’s] mercy in nesting time. Few succeed in rearing a brood of young. It is common in the woods to hear Vireos lamenting for their young that the Jay has forcibly carried away. Vast numbers of eggs are eaten and the nests torn up.”
Still, I cannot help admiring Blue Jays, because they have good traits as well. They are cunning, inquisitive, good mimics, and full of mischief. It is difficult to paint them in their true colors. Some writers call them bullies and cowards. Perhaps they deserve these names at times, but they possess courage in the defense of their young. But it is unfortunate that they show so little consideration for the feelings of other birds.
It is astonishing how accurately the Blue Jay is able to imitate the various calls and cries of other birds. These will readily deceive anyone. They seem to delight in playing tricks on their unsuspecting neighbors in this manner, apparently out of pure mischief. They are especially fond of teasing owls, and occasionally hawks; however, sometimes this has disastrous results for the Blue Jays.
From what source does the author get his information about how blue jays can be mean to other birds?
From a scientific article about blue jays
From illustrations of blue jays that he has viewed
From what a friend has said when writing to him
From conclusions he has drawn based on observing other types of birds
From what a friend has said when writing to him
The author talks about how blue jays can be mean to other birds in the first paragraph, which says, "Even their best friends can’t say much in their favor, though. They destroy many of the eggs and young of our smaller birds." After this, it states, "A friend of mine writes . . . " and then begins providing more information about how blue jays are mean to other birds in the form of a quotation from the author's friend. For example, the quotation says, "Vast numbers of eggs are eaten and the nests torn up." Based on this evidence, we can tell that the author gets his information about how blue jays can be mean to other birds "From what a friend has said when writing to him." The passage doesn't mention any scientific articles about blue jays or illustrations about blue jays, and the author doesn't ever describe other types of birds that he himself has seen in person and use this information to figure anything out about blue jays.
Example Question #1 : Using Evidence To Support A Point
Passage One
Ecuador, in South America, is home to 417 types of frogs and toads. Many of these species, or types of frogs, are at risk of dying out. In the last 50 years, many amphibian species have gone extinct. Salamanders, frogs, and toads are all amphibians. Amphibians are animals that spend part of their life in water and part on land and have backbones. Amphibians must live near water. Amphibian habitats can be found in forests, woodlots, meadows, springs, wetlands, streams, rivers, lakes, ponds, bogs, marshes. Frogs and toads are in trouble because their habitats are being destroyed as trees are being cut down to make room for farms and roads. Wetland spaces where frogs live are being drained and paved over. As these spaces are removed, the places frogs, toads, and salamanders can live shrink.
Amphibians also absorb pollution easily, because they breathe through their skin. Amphibians are usually the first to disappear when an environment is under threat from pollution. Due to pollution, some frogs are born with deformed, or wrongly shaped, body parts, such as extra legs and eyes. Frogs with deformed body parts are a clue for scientists that an environment is suffering. Between the destruction of their habitats and risks to frogs from pollution, frogs are at risk of endangerment and extinction. Scientists are working to save amphibians. Scientists want the government to pass laws that protect amphibian habitats and limit pollution.
Passage Two
My name is Maria and I am an amphibian conservation biologist. This means I am a scientist who studies and protects frogs, toads, and salamanders. My job is to protect amphibians and their natural habitats, share this knowledge with the public, and research ways to help reintroduce frogs in captivity back into the wild. I have the best job in the world. I work in a zoo, but I often travel to places like Brazil to observe amphibians in their natural habitats in the wild. Brazil, for example, has 1,022 different types of frogs, toads, and salamanders! In my work at the zoo, I specialize in only a small portion of that number. Here in the zoo, we have many amphibians in our care because some or all of their natural habitats, or homes, were destroyed. We are not alone in our work to protect amphibians. Many people, in many kinds of jobs, are helping protect amphibians and their habitats. I partner with other scientists and lawyers, like my friend Fernanda, to help create laws that best support the conservation, or protection, of amphibians. Fernanda is an environmental lawyer who works to create laws that protect diverse wildlife. She, in turn, needs to partner with government workers to help get laws passed. Together, our goal is to work together to build a world where these amphibians have a safe space to live outside of the zoo, in their natural habitat, protected from pollution or loss of space. We are working with a facility in Brazil to build a safe wild space for amphibians to be released from the zoo and into a place where they can thrive. The new habitat will be a protected wetland for these amphibians.
From what source did the author of Passage 2 most likely get her evidence about a new protected wetland habitat for amphibians in Brazil?
A website describing habitats of different frogs
A nonfiction book on frog habitats
A scientific journal about amphibians
A work team she is a part of that is building this space
A work team she is a part of that is building this space
The text says “We are working with a facility in Brazil to build a safe wild space for amphibians to be released from the zoo and into a place where they can thrive.” This shows that she likely knows about this project from firsthand evidence because she is working on the team to help build it.
Example Question #4 : Using Evidence To Support A Point
Passage One
Ecuador, in South America, is home to 417 types of frogs and toads. Many of these species, or types of frogs, are at risk of dying out. In the last 50 years, many amphibian species have gone extinct. Salamanders, frogs, and toads are all amphibians. Amphibians are animals that spend part of their life in water and part on land and have backbones. Amphibians must live near water. Amphibian habitats can be found in forests, woodlots, meadows, springs, wetlands, streams, rivers, lakes, ponds, bogs, marshes. Frogs and toads are in trouble because their habitats are being destroyed as trees are being cut down to make room for farms and roads. Wetland spaces where frogs live are being drained and paved over. As these spaces are removed, the places frogs, toads, and salamanders can live shrink.
Amphibians also absorb pollution easily, because they breathe through their skin. Amphibians are usually the first to disappear when an environment is under threat from pollution. Due to pollution, some frogs are born with deformed, or wrongly shaped, body parts, such as extra legs and eyes. Frogs with deformed body parts are a clue for scientists that an environment is suffering. Between the destruction of their habitats and risks to frogs from pollution, frogs are at risk of endangerment and extinction. Scientists are working to save amphibians. Scientists want the government to pass laws that protect amphibian habitats and limit pollution.
Passage Two
My name is Maria and I am an amphibian conservation biologist. This means I am a scientist who studies and protects frogs, toads, and salamanders. My job is to protect amphibians and their natural habitats, share this knowledge with the public, and research ways to help reintroduce frogs in captivity back into the wild. I have the best job in the world. I work in a zoo, but I often travel to places like Brazil to observe amphibians in their natural habitats in the wild. Brazil, for example, has 1,022 different types of frogs, toads, and salamanders! In my work at the zoo, I specialize in only a small portion of that number. Here in the zoo, we have many amphibians in our care because some or all of their natural habitats, or homes, were destroyed. We are not alone in our work to protect amphibians. Many people, in many kinds of jobs, are helping protect amphibians and their habitats. I partner with other scientists and lawyers, like my friend Fernanda, to help create laws that best support the conservation, or protection, of amphibians. Fernanda is an environmental lawyer who works to create laws that protect diverse wildlife. She, in turn, needs to partner with government workers to help get laws passed. Together, our goal is to work together to build a world where these amphibians have a safe space to live outside of the zoo, in their natural habitat, protected from pollution or loss of space. We are working with a facility in Brazil to build a safe wild space for amphibians to be released from the zoo and into a place where they can thrive. The new habitat will be a protected wetland for these amphibians.
In Passage 1, which sentence provides evidence to support the claim that “Amphibians must live near water”?
“Wetland spaces where frogs live are being drained and paved over.”
“Frogs and toads are in trouble because their habitats are being destroyed as trees are being cut down to make room for farms and roads.”
“As these spaces are removed, the places frogs, toads, and salamanders can live shrink."
“Amphibians are animals that spend part of their life in water and part on land, and have backbones.”
“Amphibians are animals that spend part of their life in water and part on land, and have backbones.”
The sentence “amphibians are animals that spend part of their life in water and part of their life on land”, is evidence that amphibians must live near water. If part of its life cycle has to happen in the water, it shows that an amphibian needs to live near water.
Example Question #1 : Using Evidence To Support A Point
Passage One
Ecuador, in South America, is home to 417 types of frogs and toads. Many of these species, or types of frogs, are at risk of dying out. In the last 50 years, many amphibian species have gone extinct. Salamanders, frogs, and toads are all amphibians. Amphibians are animals that spend part of their life in water and part on land and have backbones. Amphibians must live near water. Amphibian habitats can be found in forests, woodlots, meadows, springs, wetlands, streams, rivers, lakes, ponds, bogs, marshes. Frogs and toads are in trouble because their habitats are being destroyed as trees are being cut down to make room for farms and roads. Wetland spaces where frogs live are being drained and paved over. As these spaces are removed, the places frogs, toads, and salamanders can live shrink.
Amphibians also absorb pollution easily, because they breathe through their skin. Amphibians are usually the first to disappear when an environment is under threat from pollution. Due to pollution, some frogs are born with deformed, or wrongly shaped, body parts, such as extra legs and eyes. Frogs with deformed body parts are a clue for scientists that an environment is suffering. Between the destruction of their habitats and risks to frogs from pollution, frogs are at risk of endangerment and extinction. Scientists are working to save amphibians. Scientists want the government to pass laws that protect amphibian habitats and limit pollution.
Passage Two
My name is Maria and I am an amphibian conservation biologist. This means I am a scientist who studies and protects frogs, toads, and salamanders. My job is to protect amphibians and their natural habitats, share this knowledge with the public, and research ways to help reintroduce frogs in captivity back into the wild. I have the best job in the world. I work in a zoo, but I often travel to places like Brazil to observe amphibians in their natural habitats in the wild. Brazil, for example, has 1,022 different types of frogs, toads, and salamanders! In my work at the zoo, I specialize in only a small portion of that number. Here in the zoo, we have many amphibians in our care because some or all of their natural habitats, or homes, were destroyed. We are not alone in our work to protect amphibians. Many people, in many kinds of jobs, are helping protect amphibians and their habitats. I partner with other scientists and lawyers, like my friend Fernanda, to help create laws that best support the conservation, or protection, of amphibians. Fernanda is an environmental lawyer who works to create laws that protect diverse wildlife. She, in turn, needs to partner with government workers to help get laws passed. Together, our goal is to work together to build a world where these amphibians have a safe space to live outside of the zoo, in their natural habitat, protected from pollution or loss of space. We are working with a facility in Brazil to build a safe wild space for amphibians to be released from the zoo and into a place where they can thrive. The new habitat will be a protected wetland for these amphibians.
In Passage 1, what sentence provides evidence that frogs help scientists know if an environment is polluted?
“Frogs with deformed body parts are a clue for scientists that an environment is suffering.”
“Due to pollution, some frogs are born with deformed, or wrongly shaped, body parts, such as extra legs and eyes.”
“Amphibians are usually the first to disappear when an environment is under threat from pollution.”
“Amphibians also absorb pollution easily, because they breathe through their skin.”
“Frogs with deformed body parts are a clue for scientists that an environment is suffering.”
While all of these choices show that frogs are vulnerable to pollution, this answer provides evidence that frogs harmed by pollution show scientists an environment is polluted and suffering.
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