OFFICIAL EXPLANATION
Numerous vegetarians believe that there are, doubtlessly, a wealth of good reasons to stop eating meat.(A) vegetarians believe that there are, doubtlessly,
Incorrect.
This answer choice is grammatically incorrect. The singular subject a wealth of good reasons does not agree with the plural verb are.
What helps us identify this question as a Subject Verb Agreement question as well as identify the mistake are the following Stop Signs:
an X of Y subject
verb precedes subject
Notice that this sentence is comprised of two clauses. The main clause is: Numerous vegetarians believe that, and the secondary clause is there are, without doubt, a wealth of good reasons to stop eating meat.
The Subject-Verb Agreement mistake is in the secondary clause, not in the main clause.
Note that the verb are comes BEFORE the subject, a wealth of good reasons. Such an awkward sentence construction is usually used by the question writers to hide a subject-verb agreement error, so be on the lookout.(B) vegetarians believe that there are, undoubtedly,
Incorrect.
This answer choice repeats the original Subject verb Agreement mistake. The singular subject a wealth of good reasons does not agree with the plural verb are.
Note that the verb are comes BEFORE the subject, a wealth of good reasons. Such an awkward sentence construction is usually used by the question writers to hide a subject-verb agreement error, so be on the lookout.(C) vegans believe that there is, without a doubt,
Incorrect.
While this answer choice corrects the original Subject Verb Agreement mistake, by changing the plural verb are to the singular verb is, it changes the original meaning by replacing the word vegetarians with the word vegans.(D) vegetarians believe that there are, undeniably,
Incorrect.
This answer choice repeats the original Subject verb Agreement mistake. The singular subject a wealth of good reasons does not agree with the plural verb are.
Note that the verb are comes BEFORE the subject, a wealth of good reasons. Such an awkward sentence construction is usually used by the question writers to hide a subject-verb agreement error, so be on the lookout.(E) vegetarians believe that there is, without a doubt,
This answer choice corrects the Subject Verb Agreement mistake in the original question, by changing the plural verb are to the singular verb is.