3.― I’d like a single room,please?

3.― I’d like a single room,please?
― ________________.
A.You have a room on the third floor?B.The Jefferson Hotel is quite good.
C.You are going to stay in our hotel?D.Do you want a room with a bath?
4.― Do you mind if I sit here?
― ________________.
A.Yes,I’m not sitting.B.Yes,I’m busy.
C.Don’t mention it.D.I’m sorry,but I do.