Examkin

Question

Difficulty: HardSubject-Verb Agreement

A team of marine biologists is currently monitoring the health of the Great Barrier Reef. The sudden increase in temperature and salinity, along with the rising acidity of the ocean waters, have threatened the survival of these marine habitats. If these trends continue, the consequences will be devastating.

Which of the following options is the correct replacement for the underlined portion?

  1. A
    NO CHANGE
  2. has threatenedAnswer
  3. C
    were threatening
  4. D
    was threatening

Answer

has threatened
The singular subject 'increase' requires a singular verb. The present perfect form 'has threatened' maintains grammatical agreement and matches the present-tense context of the surrounding sentences ('is currently monitoring', 'continue').

Step-by-Step Solution

1
Identify the true subject of the verb in the sentence.
The subject is the singular noun 'increase'.
The noun phrase 'in temperature and salinity' is a prepositional phrase, and the phrase 'along with the rising acidity of the ocean waters' is a parenthetical modifier. Neither of these changes the singular nature of the subject.
2
Determine the correct verb number (singular or plural).
A singular verb is required to agree with 'increase'.
Subject-verb agreement requires a singular subject to pair with a singular verb form.
3
Analyze the tense of the surrounding context to ensure consistency.
The present perfect tense 'has threatened' is correct.
The passage establishes a present time frame ('is currently monitoring', 'continue', 'will be'). The present perfect tense correctly links the past/ongoing action to the present situation without an unnecessary tense shift.

Key Concept

Subject-Verb Agreement
Rate this question

Topics

Subject-Verb Agreement

More questions from this topic