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Question

Difficulty: MediumSubject-Verb Agreement

In deep-sea marine biology, the migration of bioluminescent organisms living near hydrothermal vents ______ a crucial role in nutrient distribution across oceanic layers. By tracking these vertical movements, researchers have gathered extensive data indicating that these biological processes help sustain complex ecosystems in the otherwise nutrient-poor bathypelagic zone.

Which choice completes the text so that it conforms to the conventions of Standard English?

  1. playsAnswer
  2. B
    play
  3. C
    have played
  4. D
    are playing

Answer

plays
The singular verb 'plays' correctly agrees with the singular subject of the sentence, 'migration'. The plural nouns 'organisms' and 'vents' are part of a prepositional phrase modifying the subject and do not affect the subject-verb agreement.

Step-by-Step Solution

1
Identify the true subject of the verb in the sentence.
The subject is the singular noun 'migration'. The phrase 'of bioluminescent organisms living near hydrothermal vents' is a prepositional phrase with a participial modifier that describes the migration, but it does not change the subject's number.
Determining the correct subject is necessary to establish subject-verb agreement.
2
Determine the grammatical number and tense required for the verb.
The singular subject 'migration' requires a singular verb. The rest of the passage uses the present tense ('help sustain'), indicating that the simple present tense is appropriate.
The verb must agree in number with the subject and maintain tense consistency with the surrounding context.
3
Select the option that provides the singular, present-tense form of the verb.
The singular, present-tense verb is 'plays'.
Only 'plays' is singular and fits the simple present aspect of the sentence.

Key Concept

Subject-Verb Agreement
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Topics

Subject-Verb Agreement

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