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

The sentence requires a modal verb to express a logical deduction about a past situation. The phrase "because he didn't go straight in" provides evidence leading to the conclusion about his nervousness.

Must have been is the correct choice here, as "must have + past participle" is used to make confident deductions about past events based on evidence.

Other options are inappropriate: "ought to have" and "should have" express unfulfilled obligations, while "had to" indicates past necessity rather than deduction.

Answer: B