18.Waiter: Excuse me, sir. You cannot smoke in here.
Bob: Why? I didn’t see any “No Smoking” sign.
Waiter: _______________
Bob: Oh, I didn’t know that. I’ll step out to smoke.
(A) Who said anything about smoking?
(B) Sorry, the last guest was probably smoking.
(C) Would you like smoking or non-smoking?
(D) Smoking is not allowed inside all public buildings.