I can't hear what my mother is ___ the boy.A.telling B.speaking C,talki

I can't hear what my mother is ___ the boy.A.telling B.speaking C,talki
I can’t hear what my motheris ___ the boy.
A.telling B.speaking C,talking D.saying to
求详解
主要讲一下A和D选项哪一个？为什么？