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.