—I’m sorry to have kept you waiting.— Bill. A. You’re welcomeB. Go aheadC. Don’t mention

问题补充：

—I’m sorry to have kept you waiting.

—, Bill.

A. You’re welcome

B. Go ahead

C. Don’t mention it

D. No problem

答案：

A. You’re welcome

B. Go ahead

C. Don’t mention it

(答案→)D. No problem

解析：对道歉的应答常见的有：That’s all right /That’s OK / That’s nothing / Never mind / It doesn’t matter / No problem等，意为“没关系”。而Don’t mention it是用来回答对方表示感谢时的用语。