听力原文:W: Excuse me, Professor Hill, may I ask you a few questions?
M: Yes, of course, But I'm sorry I have a class to attend. Why don't you come in my office hours, that's 4 to 5 p.m, Monday, Thursday and Friday?
Why can't Professor Hill answer her questions now?
A. He doesn't have time
B. It's not his office hour.
C. He is too tired after class.
D. He will only be available in the afternoon.