Choose the most suitable option to replace the highlighted part of the sentence:
Three hours is the duration of the exam.
Show answer & explanation
Correct answer: C
Explanation
The original sentence is grammatically correct. When a plural noun like 'hours' refers to a single unit of time, money, or distance, it is treated as a singular subject and takes a singular verb ('is'). Options A and B use the plural verb 'are,' which is incorrect in this context. Option D uses the past tense 'were,' which changes the intended meaning of the original sentence. Therefore, option C is the only correct choice that maintains both the grammar and the meaning.