Smith : Oh, it's ten o'clock. I'd better go now.

Host : ___________

A. Ok. Please walk slowly.

B. Why do you want to go now? Don't you want to stay?

C. Won't you stay for another cup of coffee?

D. Yeah, it's really late. Why not immediately?

C【解析】客人说再见，而主人尽力挽留多待一会是符合人之常情的。C项是更佳选择；特别注意的是A项，它是中文式的表达习惯，一定要避免。