The prefixes im- and un- are both negation prefixes; this means they take the original meaning of the word and cause the new word to mean the opposite. Something that is “assailable” is able to be assailed, able to be conquered and something that is “pregnable” is able to be penetrated, able to be conquered. “Unassailable” and “impregnable” are therefore synonyms of one another: both words mean not able to be conquered. To solve this analogy you have to identify the best available synonym for “meager.” “Meager” means to have very little of something, to be in very small supply so the best synonym is “scant.” To provide further help, “excessive” means too much; “unstoppable” means unable to be stopped; “credible” means believable; “mischievous” means badly-behaved, naughty.  

The prefix neo- means new, and the suffix -lithic refers to an era of prehistory. The prefix paleo- means old or very ancient, so the correct answer choice is “Paleolithic.” The other four answer choices are all other eras of ancient history, the key to solve this analogy was identifying the relationship between neo- and “new” and paleo- and “old.”

The prefix mand- means command, so something that is “mandatory” is something you are commanded to do and have to do. As such, it is a synonym of “required,” so to solve this analogy you need to determine the best available synonym for “intermittent.” The prefix inter- means between, and the word fragment -mit- means send so something that is “intermittent” is sent back and forth at irregular, or varied, intervals. As such it is closest in meaning to “irregular,” which means not frequent, out of pattern. The prefix ir- negates the meaning of the original word “regular,” causing the new word to mean the opposite. To provide further help, “frequent” means often; “abrasive” means rude; “laborious” means hard-work; “gregarious” means friendly, sociable.

A fish uses its gills to breathe, so to solve this analogy, you need to pick out a word that describes what part of its body a squirrel uses to breathe. The correct answer is "lungs." None of the other answer choices describe the body part that a squirrel uses to breathe.

The root "agr­-" means having to do with farming or rural life, so it makes sense that "agriculture" and "farming" are synonyms. To solve this analogy, you need to pick out the answer choice that is a synonym of "horticulture." "Horticulture" is derived from the Latin "hortus," meaning garden, and is a synonym of "gardening." So, "gardening" is the correct answer.

"Marriage" is an institution that is ended by "divorce." To solve this analogy, you have to determine which of these words describes the ending of a "contract." A "contract" is a binding agreement between two parties. When a "contract" is ended, it is said to be "terminated." It may have helped you arrive at this answer if you considered that the prefix "term-" means boundary, ending. To provide further, help, an "accord" is an agreement; "litigation" is the process of suing someone; an "anniversary" is a yearly rememberance of a specific event on a specific date, such as a birthday; "slander" is the act of writing untruthful statements about someone with the intent of negatively affecting their reputation. 

“Terrestrial” is an adjective that means having to do with the earth, so we need to pick out a noun that conveys what the adjective “celestial” refers to. “Celestial” means having to do with sky, heaven, or outer space, so while all of the answer choices describe places or land features, “celestial” refers to something that has to do with "outer space" just as “terrestrial” refers to something that has to do with the earth. So, “outer space” is the correct answer.

An octopus has eight legs, as you might be able to infer because the word "octopus" contains the prefix "octo-" at the beginning of the word. "Octo-" means eight, and appears in other words like "octagon" (an eight-sided shape). To solve this analogy, if you don't know how many legs a centipede has, you can still arrive at the correct answer by using the prefix "cent-" as a clue to infer this information. "Cent-" means one hundred and appears in other words like "centimeter" (a unit of measurement that is one-hundredth of a meter) and "century" (a span of time of one hundred consecutive years).

A nine-sided shape is called a "nonagon," and an eight-sided shape is called an "octagon." The prefix "non-" suggests that the word will have to do with the number nine. Likewise, the prefix "oct-" suggests that the word will have to do with the number eight. (For an example of this, just think of how an "octopus" has eight legs!)

“Tertiary” is an adjective that means third, so we need to pick out an answer choice that is synonymous with “quaternary.” While all of the answer choices might look like potentially correct answers, “quaternary” is an adjective that means fourth, so “fourth” is the correct answer. You can also use prefixes as context clues to help you solve this quesiton: "tertius" is Latin for third and has influenced the prefix "tri-," while "quattuor" is Latin for fourth and has influenced English words like "quad" and "quarter."