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Question

Difficulty: MediumSubject-Verb Agreement

Read the passage and answer the question that follows.

Deep-sea sediment cores retrieved from the Arctic Ocean contain microscopic fossils of marine organisms known as foraminifera. The chemical composition of these fossils, which accumulated on the ocean floor over millions of years, help scientists reconstruct past global temperatures. By analyzing the oxygen isotopes within the shells, researchers can determine the extent of prehistoric ice sheets.

Which of the following is the best revision of the underlined portion?

  1. A
    NO CHANGE
  2. helpsAnswer
  3. C
    are helping
  4. D
    helped

Answer

The singular present-tense verb 'helps' is correct because it agrees with the singular subject 'composition'.
The singular present-tense verb 'helps' is correct because it matches the singular subject 'composition'. The plural nouns 'fossils' and 'years' are parts of modifying prepositional and relative clauses and do not affect the grammatical number of the subject.

Step-by-Step Solution

1
Identify the subject of the clause containing the underlined verb.
The subject is 'composition', which is a singular noun.
The verb must agree in number (singular vs. plural) with its true grammatical subject, not with the nouns inside intervening phrases.
2
Identify and ignore intervening phrases and clauses that separate the subject from the verb.
The prepositional phrase 'of these fossils' and the relative clause 'which accumulated on the ocean floor over millions of years' both contain plural nouns ('fossils', 'years'), but they do not change the singular nature of the subject 'composition'.
Intervening modifier phrases do not affect subject-verb agreement.
3
Determine the correct verb form and tense based on the subject and the surrounding context.
A singular, present-tense verb ('helps') is required to agree with 'composition' and match the present-tense timeline established by 'contain' and 'can' in the surrounding sentences.
Using a plural verb or shifting to the past tense would violate rules of agreement and tense consistency.

Key Concept

Subject-Verb Agreement with Intervening Phrases
Estimated Time:1m 0s
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Topics

Subject-Verb Agreement

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