【单选题】

Woman: Now, Richard, would you care to explain how the answers to the test questions appeared on your desk Man: I can't, Professor Harley. Someone must have left them on my desk. Question: What is the man's problem
A．He is suspected of cheating.

B．He left the answers on his desk.
C．He doesn't know how to explain.
D．He didn't know the answers to the questions.