Which of the following italicized parts is a subject clause？A．I"ve an idea that she likes

Which of the following italicized parts is a subject clause？

A．I"ve an idea that she likes him better than anyone else.

B．It is quite clear that the whole project is doomed to failure.

C．He told me that he would go to college the next year.

D．The school that he once studied in is very famous.

请帮忙给出正确答案和分析，谢谢！