To catch this sentence's error, you must understand the distinction between the homonyms "then" and "than." "Then" refers to an event that happens after something, as in the sentence, "She went to the movies and then to the store." "Than" compares two words or phrases, as in the sentence, "Driving is much faster than walking." To correct the sentence's error, "then" should be changed to "than."

You must understand the distinction between common homonyms to pick out the error in this sentence, particularly between "its" and "it's," as well as between "whose" and "who's." "Its" is a possessive pronoun, identifying something that belongs to "it," so the phrase "I bet its owner is looking for it" is correct. You can eliminate that answer choice from your options. However, "who's" is a contraction of the words "who" and "is," which does not fit in this sentence ("I'm not sure who is jacket this is" wouldn't make sense) and is therefore an error. "Whose" is a possessive pronoun, signaling that the noun belongs to someone, so that would be the correct form here. ("I'm not sure whose jacket this is").

"Affect" and "effect" are two commonly confused homonyms. The best way to remember the difference between them is to remember that one is used most often as a noun and the other as a verb. "Affect" is a verb that means to influence something, while "effect" is a noun that means the result of something. ("Effect" can also be used as a verb that means to cause, as in the phrase "effect change.") One should use the word "effect," not the word "affect," in this sentence.

This sentence's error has to do with the homonyms "to," two," and "too." The "two" in "two large slices of chocolate cake" is correct; this form of the word refers to the whole number greater than one but less than three. The "to" in "to her friend's birthday party" is also correctly used; this "to" is being used as a preposition. The "to" in "to make odd gurgling noises" is also correctly used because it is part of an infinitive verb, "to make." The "to" in "eaten to much" is incorrect, however; to correct the sentence, one would need to change this "to" to "too," which is used to mean in excess or in an amount that is greater than what is needed or desired.

This sentence's error is its use of "than," a word that is used to form comparisons like "He is taller than her," where it needs to use "then," which is a word that designates a specified time in a sequence in the past, as in the sentence "I almost bought the giant purple trampoline for my apartment, but then I decided not to." To correct this sentence, "than" should be changed to "then."

You must understand the distinction between the homonyms "its" and "it's" to correctly answer this question. "It's" is a contraction of "it" and "is" and is used in sentences like "It's too early to go to sleep." "Its," on the other hand, is a possessive pronoun, identifying something that belongs to "it." "Its" is used in sentences like "The cat played with its toy." So, to correct this sentence's error, "it's" needs to be changed to "its."

"Which” is used to show that there is modification to a phrase when the modification comes after a comma. “That” is used to show that there is a modification to a phrase in which there is not a comma after the subject being modified. Here, the subject being modified is “mitochondria,” and is followed by a comma. Therefore, the word modifying that subject should be “which.”

“Which” is used to show that there is modification to a phrase when the modification comes after a comma. “That” is used to show that there is a modification to a phrase in which a comma does not follow the subject being modified. Here, the subject being modified is “kitten,” but there is no comma after it. Therefore, “that” is appropriate, not “which.”

“Which” is used to show that there is modification to a phrase when the modification comes after a comma. “That” is used to show that there is a modification to a phrase in which there is not a comma after the subject being modified. Here, the first part of the sentence preceding the comma is the part that is being modified. Therefore, "which" should be used instead of "that."

“Which” is used to show that there is modification to a phrase when the modification comes after a comma. “That” is used to show that there is a modification to a phrase in which there is not a comma after the subject being modified. Here, the part of the sentence before the comma is being modified by the part of the sentence after the comma. Therefore, “which” is appropriate, not “that.”