--I will go to Hainan next week.A.Have a good trip! B.Good idea. C.Thank you.

问题补充：

--I will go to Hainan next week.

--

A.Have a good trip! B.Good idea. C.Thank you.

答案：

解析：句意：下周我要去海南。祝你旅途愉快！Good idea.好主意Thank you.谢谢你。作为上句的回答都不合适，故选A。