Speaker A: Uh, I wonder if I could possibly use your phone.Speaker B: ______

A．Oh, I'm sorry, but it isn't working; it's out of order.

B．You are welcome. It's over there.

C．Of course. Who are you going to call

D．Yes, you can, But don't you see a public phone booth over there

龋病病因的四联因素是（）

A.细菌、菌斑、宿主和食物因素

B.细菌、宿主、食物和时间因素

C.菌斑、宿主、牙排列拥挤和时间因素

D.蔗糖、细菌、宿主和遗传因素

E.菌斑、唾液分泌、营养和时间因素