OG 124 -support是什么词性，好像没人问过？

124. During Roosevelt’s years in office Black Americans began voting for Democrats rather than Republicans in national elections, but Black support for Democrats at the state and local levels developed only after when civil rights legislation was supported by Harry Truman.

(A) developed only after when civil rights legislation was supported by Harry Truman

(B) developed only after when Harry Truman supported civil rights legislation

(C) developed only after Harry Truman’s support of civil rights legislation

(D) develops only at the time after the supporting of civil rights legislation by Harry Truman（C）

(E) developed only after there being Harry Truman’s support of civil rights legislation

下面的SUPPORT 应该是 名词， 可是Black 后面为什么没有‘S 呢？（c 里就有）

but Black support for Democrats at the state and local levels developed only after when civil rights legislation was supported by Harry Truman.

多谢

Black support 习惯表达吧，我用google搜，一大把。BTW, Black's support 也不错。Black这里小写可能也行。

Black Americans and Black support here i think have the same meaning.support stands for people, so we do not have to say black's  Americans. open to discuss...