急救:一道语法题目!!!!:)谢谢

An attempt to ratify the Equal Rights Amendment,begun almost two decades ago,has been unsuccessful despite efforts by many important groups,including the National Organization for Women.

A  to ratify the Equal Rights Amendment,begun almost two decades ago ,

B begun almost two decades ago,for ratifying the Equal Rihts Amendment

C begun for ratifying the Equal Rights Amendement  almost two decades ago

D at ratifying the Equal Rights Amendment,begun almost two decades ago,

E  that has begun almost two decades ago to ratify the Equal Rights Amendment

答案是a,为什么啊>

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可以参考：

http://forum.chasedream.com/dispbbs.asp?boardID=23&ID=79830&page=1