Question

Direction: In the questions given below, choose the most appropriate option to replace the underlined part keeping in mind grammatical correctness.
The flippers or tail of a whale or seal lack insulating blubber, but countercurrent heat exchangers {greatly reduce heat loss in these extremities, as it does in the legs of many birds.

• A. greatly reduce heat loss in these extremities, as it does in the legs of many birds.
• B. greatly reduce heat loss in the extremities, as it does in the legs of many bird.
• C. greatly reduce heat loss in these extremities, as they do in the legs of many birds.
• D. greatly reduce heat lose in these extremities, as these do in the legs of many birds.

Hint:

Plural subject → plural pronoun
heat exchangers → they do (not it does)

Answer 1

The Correct Option is C

Concept: This question tests subject-verb agreement and pronoun consistency.

Step 1: Identify the subject.
The subject is “countercurrent heat exchangers” (plural).

Step 2: Check pronoun agreement.
The pronoun referring back to a plural subject must also be plural: \[ \text{they do (correct)} \quad \text{not} \quad \text{it does} \]

Step 3: Evaluate options.

• (A) uses singular “it does” $\times$
• (B) “many bird” incorrect $\times$
• (C) correct plural agreement $\checkmark$
• (D) “heat lose” incorrect $\times$

Step 4: Conclusion.
Thus, the correct answer is (C).