The topic a heated discussion.A. set offB. set outC. set downD. set for

问题补充：

The topic a heated discussion.

A. set off

B. set out

C. set down

D. set for

答案：

(答案→)A. set off

B. set out

C. set down

D. set for

解析：考查词组：A. set off出发，引发，引爆，B. set out出发，开始，C. set down记下，D. set for为…安排，句意：这个话题引发了一场热烈的讨论。选A。