The expert offered us another piece of advice , ___ of great help to our program.

A．I think it is

B．I think which is

C．which I think it is

D．which I think is

矿用汽车多采用（）驱动布置方式。

A.4×2后轮

B.4×4后轮

C.4×2前轮

D.2×2后轮