[求助]关于比较 倒装，请指教

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

(A)   against their struggle for social legitimacy than

(B)   in their struggle for social legitimacy than did

(C)   against their struggle for social legitimacy as

(D)   in their struggle for social legitimacy as did

什么时候  in their struggle for social legitimacy than did 这个did 可以省略啊 我记得好像有题目可以不用的

还有这道题目中opposition 为什么不搭配 against

我选的是A啊

请牛牛分析。。。感激不尽。