--Drivers in England drive cars on the left of the roads. 

--                    .

A．So Australian drivers are.

B．So are Australian drivers.

C．So do Australian drivers.

D．So Australian drivers do.

按照危机分类，下列属于社会问题的是（）。

A、劳资关系问题

B、大规模疾病传播

C、自然灾害

D、敲诈勒索