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.
Why is John NOT sure that he wants to join the group

A.He doesn’t have an instrument of his own.
B.He doesn’t like to play in small groups.
C.He doesn’t think he can play well enough.
D.He doesn’t know if he has enough free tim