The telephone rang but I didn’t hear it. I _________ asleep.

A．must be

B．ought to have been

C．should be

D．must have been

调查上水管线、雨水管线、污水管线、热力管线、燃气管线、电力和电信管线的现状及规划目标和其可能实现的时间，不属于房地产开发项目可行性研究的主要内容。（）