Bunuel
The starling, a non-native bird species introduced to the United States to control insects, are now the country’s most common bird.A. The starling, a non-native bird species introduced to the United States to control insects, are now the country’s most common bird.
B. Starlings are a species of non-native bird introduced to the United States to control insects and now the country’s most common bird.
C. The starling is a non-native bird species introduced to the United States to control insects and is now the country’s most common birds.
D. Starlings are a non-native bird species introduced to the United States to control insects and now the country’s most common birds.
E. The starling, a non-native bird species introduced to the United States to control insects, is now the country’s most common bird.
VERITAS PREP OFFICIAL SOLUTION:
The easiest decision point to deal with on this problem is that of subject-verb agreement. The only difference between (A) and (E) is that (A) uses "are" while (E) uses "is," a telltale sign that you need to determine what the subject of the sentence is. For each choice that subject is the singular "the starling," so the plural verb "are" is incorrect and you can eliminate (A).
Choice (C) also commits a singular-vs.-plural error, leading with "the starling" but calling it "the nation's most common birds," plural. (C) is therefore incorrect.
Choices (B) and (D) correct the subject-verb agreement error by matching the plural "starlings" with the plural "are." But note that each leaves itself open to a logical meaning error. if you slash-and-burn away some excess description, the core of those sentences is:
Starlings are a species introduced to eliminate insects and now the nation's most common bird(s).
While at first glance that might seem logical (Starlings are X and Y), note the placement of "and" could lead people to read the sentence as "Starlings were introduced to eliminate insects and now birds" - an illogical meaning as you cannot change the reason that starlings were introduced ("and now birds" suggests that change). This lack of clarity and ultimately illogical meaning means that (B) and (D) are incorrect, leaving
(E) as the correct answer.