A、  B、  C、  B问题的前半句叙述了某一事实，后面附加了问句，问听话者是否知道这个事实。(B)回答说不知道这件事，很想知道原因，因此是正确答案。(A)和(C)的No和Not at all虽然是合适的回答，但后半句的内容

Which room should I reserve for the meeting?
(A) It’s at 8, tomorrow.
(B) For a week, please.
(C) The one facing the park.

The program’s delayed an hour, did you know?
(A) No, just fifteen minutes by taxi.
(B) Really? I wonder why.
(C) Not at all, you’re just in time.