地球上种类和数量最多的动物类群是[ ]

A．鱼类        

B．哺乳动物        

C．原生动物    

D．昆虫

I feel it is Jack as well as his wife that _______ for their son’s bad performance at school.

A．are to blame

B．is to be blamed

C．are to be blamed

D．is to blame