A、Her friend. B、Her friend’s son. C、Her son. D、Her friend and her son. A根据I have a friend Mary..., and she suggested I call you.

W: Hi, my name is Christa and I have a friend Mary, whose son is taking guitar lessons from you, and she suggested I call you.
M: OK. Will the lessons be for yourself or your son?
W: I want to learn. My son is only three.
M: Fine. Have you had any musical experience before?
W: Well, I studied the piano for about three months but that was 6 years ago.
M: That’s good. So we needn’t start right from the beginning again.
W: When can I take lessons and how much do they cost?
M: Well, that depends on you. We have a small group that meets on Monday and Wednesday evenings for two hours, that costs $4 an hour. Then on Tuesdays and Thursdays I give private lessons which cost $8 an hour.
W: I’m afraid that I can’t make it on Mondays but I can come on Wednesdays.