—Could you tell me_________?

—He is in the library．

A．where Simon was

B．where is Simon

C．where was Simon

D．where Simon is

若二叉树的先序遍历序列为ABDECF，中序遍历序列DBEAFC，则其后序遍历序列为（）。

A．DEBAFC

B．DEFBCA

C．DEBCFA

D．DEBFCA