F: If I were you, I would go to work by bike. It's good for health. ,M: Uh, used to, but now by bus.
(A) F: I’m sorry, I don’t understand. Could you say it again? (B) F: Did you usually go to work by bike? I don't think it benefit health. (C) F: So you used to go to work by bike. (D) F: You mean you used to go to work by bus rather than by bike.
C