— They say Tom's brother is a billionaire.

— _______? He wouldn't accept any help from his brother, even though it was offered. [ ]

A. What if

B. What for

C. So what

D. Forget it

如何在激励地方发展汽车产业积极性的同时，又能______防止产业过剩和产能泡沫，是当前汽车业界需要认真面对的一个______。
填入横线部分最恰当的一项是( )。

A．有效 难题
B．高效 课题
C．高效 难题
D．有效 课题