Question 177·Hard·Form, Structure, and Sense
In recent years, the decline in marsh sparrow populations has been linked to habitat loss, rising sea levels, and increased predation; nevertheless, biologists warn that focusing solely on these factors ______ the subtle but significant influence of contaminants that accumulate in marsh sediments.
Which choice completes the text so that it conforms to the conventions of Standard English?
For Standard English verb-formation questions, first locate the full clause around the blank and identify its subject; then decide what tense and number (singular/plural) the verb must have based on the context (general truth, ongoing action, specific past event, etc.). After that, plug in each answer choice and quickly eliminate options that are not finite verbs, do not agree with the subject, or use a tense or structure that sounds awkward or does not match the time frame implied by the rest of the sentence.
Hints
Check what comes after "warn that"
After the words "biologists warn that," the sentence should contain a full clause with its own subject and main verb. Identify that subject and think about what kind of verb it needs.
Identify the subject near the blank
In the clause after "warn that," is the subject a single thing or more than one thing? Look carefully at the phrase "focusing solely on these factors" and decide whether it is treated as singular or plural in English.
Match tense to the type of statement
Biologists are giving a general warning about what typically happens when people focus only on certain factors. What verb tense is usually used in English to describe general truths or typical results?
Step-by-step Explanation
Identify the clause structure around the blank
Look at the part of the sentence starting from "biologists":
"biologists warn that focusing solely on these factors ______ the subtle but significant influence of contaminants..."
After "warn that," we need a complete clause (a subject and a finite verb). The subject of that clause is the gerund phrase "focusing solely on these factors," which functions as a singular subject.
Determine the needed verb form
Because "focusing" is acting as a singular subject, the verb that goes in the blank must:
- Be a finite verb (not just a -ing form) so that the clause is complete.
- Agree in number with a singular subject.
- Match the general, timeless warning that biologists are giving (a typical or general result). For general truths or typical results, English usually uses the simple present tense (like "causes," "means," or "overlooks").
Test each option for grammar and meaning
Insert each option into the sentence:
- A) "focusing solely on these factors overlooking the subtle..." → leaves the clause without a proper main verb; "overlooking" is not a finite verb here.
- B) "focusing solely on these factors will have overlooked the subtle..." → awkward and incorrect tense; "will have overlooked" (future perfect) does not match a general warning.
- C) "focusing solely on these factors is to overlook the subtle..." → grammatically possible but wordy and unnatural here; it uses a linking verb structure instead of a direct, active verb describing what focusing does.
- D) "focusing solely on these factors overlooks the subtle..." → uses a simple present, singular verb that completes the clause and clearly states what this kind of focusing does.
Confirm the best, most standard choice
The option that gives a complete clause after "warn that," uses simple present tense for a general warning, and agrees with the singular subject "focusing" is D) overlooks.