Official ExplanationThe use of
Bt corn, which is corn that has been modified to produce insecticidal proteins that occur naturally in the bacterium
Bacillus thuringiensis, has reduced the producers’ use of pesticides by more than 36 percent and
have decreased the occurrence of pests in entire regions where it is planted.A. have decreased the occurrence of pests in entire regions where it is plantedB. has decreased the occurrence of pests in entire regions where they are plantedC. has decreased the occurrence of pests in entire regions where the corn is plantedD. have decreased the occurrence of pests in entire regions where plantedE. Bt corn plants have decreased the occurrence of pests in entire regions where it is plantedAfter a quick glance over the options, there are 2 main areas we can focus on:
1. have decreased / has decreased (Subject-Verb Agreement)2. it is planted / they are planted / the corn is planted / planted (Pronouns & Clarity)Since #1 on our list is a clear “either/or” split, let’s start there. We need to make sure the verb (have/has decreased) matches up with the subject (use). Since “use” is singular, let’s eliminate any options that use a plural verb:
A.
have decreased the occurrence of pests in entire regions where it is planted
B.
has decreased the occurrence of pests in entire regions where they are planted
C.
has decreased the occurrence of pests in entire regions where the corn is planted
D.
have decreased the occurrence of pests in entire regions where planted
E. Bt corn plants
have decreased the occurrence of pests in entire regions where it is planted
We can eliminate options A & D because they use a plural verb with a singular subject. Option E uses the wrong verb tense, but there is something else wrong with it: the structure. If we cross out the modifier phrase, you’ll see that what’s left over doesn’t work as a complete sentence:
The use of Bt corn,
which is corn that has been modified to produce insecticidal proteins that occur naturally in the bacterium Bacillus thuringiensis,
has reduced the producers’ use of pesticides by more than 36 percent and
Bt corn plants have decreased the occurrence of pests in entire regions where it is planted.By changing the wording, this has now become 2 independent clauses that need to be separated by a comma and conjunction - but there is no comma. It also changes the meaning of the second clause to be about “
Bt corn” instead of “the use of
Bt corn.” So we also need to eliminate this one.
Now that we have it narrowed down to only 2 options, let’s tackle #2 on our list: clarity & pronouns. We need to make sure that any pronouns have 100% clear antecedents, and we also need to check that the meaning doesn’t get distorted:
B. has decreased the occurrence of pests in entire regions where they are plantedThis is
INCORRECT because the pronoun “they” doesn’t have a clear antecedent. Is it referring back to pests, corn, pesticides, etc.? If it’s not 100% clear, it’s a vague pronoun - and the GMAT does not like vague pronouns.
C. has decreased the occurrence of pests in entire regions where the corn is plantedThis is
CORRECT! The subject-verb agreement with “use” and “has decreased” works, and it does away with pronouns entirely and simply repeats the noun that the verb “is planted” applies to. The meaning is 100% clear, so this is our answer.
There you have it - option C is the correct choice! By focusing on key differences and starting with an “either/or” split, we can narrow down our choices quickly.
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