Câu hỏi 10

Ta có: \(\left\{ \matrix{AD \subset \left( {SAD} \right) \hfill \cr BC \subset \left( {SBC} \right) \hfill \cr AD//BC \hfill \cr d = \left( {SAD} \right) \cap \left( {SBC} \right) \hfill \cr} \right. \Rightarrow d//AD//BC\)

Chọn A.