og124 未解答的问题

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

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

答案是c,我不明白画线部分是什么意思，怎么翻译？

黑人的支持是在HT提倡civil rights立法后才发展起来的。

意译。呵呵