单项选择题

Questions 4 to 7 are based on the following conversation. At the end of the conversation, you will be given 20 seconds to answer the questions. Now, listen to the conversation.
What might be a reason the man gets ill

A.He’s unwilling to be immunized.
B.He doesn’t get enough rest.
C.He forgets to take his medicine.
D.He doesn’t dress warmly enoug