He ________ have been nervous because he didn't go straight in. A. ought to B. must C. should D

He ________ have been nervous because he didn't go straight in. A. ought to B. must C. should D. had to

To determine the correct modal verb, we analyze the sentence context: it expresses a logical deduction about the past ("he was nervous") based on evidence ("he didn't go straight in").

Ought to have and should have (Options A and C) typically convey unfulfilled obligations (e.g., "He should have arrived on time"), not deductions.

Had to have (Option D) implies necessity ("He had to have known"), which doesn’t fit the inferential meaning here.

Must have (Option B) is used for confident past deductions based on evidence, exactly matching the context: the observation ("didn’t go straight in") leads to the conclusion ("was nervous").

Answer: B. must