The answer choice "the distance between the sun and the planets varies over time" is correct. It correctly uses a singular verb—"varies"—to match the singular subject, "distance."

All of the other answer choices are incorrect because they contain a subject-verb number agreement error. They use plural verb forms when they should use singular verb forms instead.

No error. The subject “the majority” is singular, so the verb must be “believes.” "The media" is plural because it refers to various sources, so the verb should be “are.”

The underlined part of the sentence contains a flaw in subject verb agreement. "No one" is properly used as a singular form. Therefore, "no one questions" is the correct answer choice.

Since "multitude" is a singular subject, its verb must be singular as well. The only answer choice that contains a singular verb is "lies"; the rest incorrectly contain plural verbs.

"There are” is correct because it indicates the existence of more than one thing (e.g., varieties). “Which” is incorrect because it does not follow a comma, nor does it refer to a complement/predicate. 

The use of the singular verb "was" is incorrect with the plural subject "members." Even though the verb is next to the singular group, the verb needs to match the subject. Thus the correct answer choice is "the group were frequently at odds," which is the only choice with the appropriate verb tense.

The subject of the sentence, "Mark and his friend Josh," is plural. Therefore, the sentence must use a verb that agrees with a plural subject. So, "are" needs to be used instead of "is." In choosing between "are a type" and "are a types," the phrase "a types" is grammatically incorrect because "a" is an indefinite article used with singular nouns, and "types" is a plural noun. Plus, you can see that the sentence is discussing one type of person "called introverts"—there is no discussion provided of any other type of person, so using the plural "types" would not make sense in the sentence's context. So, "are a type" is the correct answer.

An apostrophe is necessary to show possession, but the word “director” doesn’t need to be capitalized unless it is the official title or nickname of the person. Since “the quality” is singular, the sentence must read, "Despite positive reviews from movie critics, the quality of the young director’s recent films is rather questionable."

The underlined words, the verb phrase "have become," must be in agreement with the subject of the sentence, which is "treatment." In the sentence, treatment is singular, even though it discusses "animals in laboratories." Thus, the singular verb form "has become" is the correct answer.

The verb "hold" is a plural verb, but the subject of the sentence is the singular "The oldest." The verb needs to be changed to a singular form to be in agreement with the subject. The only answer choice that uses the correct verb is "the veterans holds a special place."