Question 240·Hard·Form, Structure, and Sense
Researchers studying the dietary habits of migratory songbirds have discovered that the birds may digest certain berries more efficiently than insects, a finding that challenges long-held assumptions about the animals’ protein requirements. The study’s authors argue that the berries’ high antioxidant content, rather than their caloric value alone, ___ the birds to recover quickly from long flights and maintain optimal muscle function.
Which choice completes the text so that it conforms to the conventions of Standard English?
For subject-verb agreement questions, first locate the true subject by crossing out extra phrases (especially prepositional phrases and contrasts like "rather than..."). Decide if that subject is singular or plural, then match it with a verb form that has the same number and an appropriate tense for the surrounding context. Finally, eliminate any options that are participles (-ing forms) or complex tenses that don’t fit the sentence’s time frame or structure.
Hints
Focus on the clause after "argue that"
Look closely at the part of the sentence starting with "that the berries’ high antioxidant content..." and decide what the main subject and verb of that clause should be.
Find the real subject
In the phrase "the berries’ high antioxidant content, rather than their caloric value alone," which single word is the core noun that the verb must agree with?
Check number and tense
Once you know the subject, ask: is it singular or plural, and what tense is being used in the rest of the paragraph? Eliminate any verb forms that don’t match.
Watch out for -ing and helping verbs
Make sure the word you choose can act as the main verb of the "that" clause, not just as a modifier or part of a different tense.
Step-by-step Explanation
Identify what the question is testing
This is a Standard English conventions question about verb form and subject-verb agreement. You need a verb that fits grammatically in the clause starting with "that the berries’ high antioxidant content..." and matches the rest of the sentence in tense and form.
Locate the subject of the verb
In the clause after "argue that," the core subject is "the berries’ high antioxidant content."
- "Content" is the main noun.
- "berries’" is possessive, describing what kind of content.
- "rather than their caloric value alone" is just a contrasting phrase and does not change the subject. So the subject is singular: "content."
Decide on singular vs. plural verb
Because the subject "content" is singular, the verb must also be singular in the present tense (forms like "is," "does," "enables").
- A plural verb (like "enable") would incorrectly treat the subject as plural.
- A participle (like "enabling") cannot serve as the main verb of the clause introduced by "that."
Match the tense and choose the best-fitting form
The rest of the passage uses present tense for general scientific claims: "have discovered," "may digest," "argue." Within the "that" clause, we want a simple present, singular verb that completes the thought: the antioxidant content ... [verb] the birds to recover quickly and maintain optimal muscle function. The only choice that is a simple present, singular verb that fits this structure is "enables."