13. The actual votes cast by incumbents can provide voters with a more accur

ate picture of their attitudes than the speeches they make while campaigning

for reelection. (Z.P. 122)

A) their attitudes than the speeches they make

B) the attitudes of incumbents than the speeches they make

C) the attitudes of incumbents than do the speeches they make

D) the attitudes of incumbents than do the speeches

E) the attitudes of incumbents than the speeches

这个题目答案是C但是我觉得do和can是连不起来的，请问各位仁兄你们怎么看