[求助]XDF section1-10

In the United states,trade unions encountered far more intecse opposition against their struggle for social legitimacy than the organized labor movements of most other democratic nations.

(B)in their struggle of social legitimacy than did

(C)against their struggle for social legitimacy as

答案选的B，我选的C ，是有什么固定搭配吗？总觉得答案不太对，请教一下大家。