help Which one is right?Why?

－Could you tell me the way to the post office?
－I am sorry,____I'm a stranger here myself.
A but B. then C.so D. otherwise

help Which one is right?Why? which one to choose Which one? Thank u. which one is better the one 和 which which one 与 which的区别 in which 与 one in which which is_,this one or that one? Which one did you choose? which is the right one?