Is this her notebook?(选择正确的答案)

问题描述:

Is this her notebook?(选择正确的答案)
A.Yes,this is.
B.No,it isn't.
C.No,it is not.
要写原因

选B,B和C表面看来一样,但是习惯说法是B,A明显不对.当问句是Is this...回答一般都是It...