客运合同成立的时间是（）。

A.承运人开始发车

B.承运人开始卖票

C.承运人把客票交到旅客手中

D.承运人截止卖票

When two power-driven vessels are meeting on reciprocal or nearly reciprocal courses so as to involve risk of collision,they shall be deemed to be in（）.

A.head-on situation

B.crossing situation

C.overtaking situation

D.close-quarters situation