单项选择题

Questions 4 to 6 are based on the following conversation. At the end of the conversation, you will be given 15 seconds to answer the questions. Now, listen to the conversation.
What did Janet almost forget to ask Professor Webster to do

A.To leave the master key for Don.
B.To put the homework on Don’s desk.
C.To give Don’s students the next assignment.
D.To call Don at the end of the afternoon.