修饰哪个词？

160.
                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 Rights Amendment

(C) begun for ratifying the Equal Rights Amendment almost two decades ago

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

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

我选了C,         Ａ的begun 不是修饰前面的amendment 吗？

这里不太容易混淆

1 因为begun前面用逗号隔开，说明begun可以修饰整个phrase

2 Amendment一般不用begun，你不能说A begins the Amendment,所以逻辑上begun修饰attempt

C的begin something for doing something不是idiomatic用法。

那意思就是，前面有逗号时，可以修饰紧前面的词，也可以修饰前面的主语是吗？ 那怎么确定？