GWD-13-1 请教！

Q19: GWD-13-1

Although she had been known as an effective legislator first in the Texas Senate and later in the United States House of Representatives, not until Barbara Jordan’s participation in the hearings on the impeachment of President Richard Nixon in 1974 was she made a nationally recognized figure, as it was televised nationwide.

1. later in the United States House of Representatives, not until Barbara Jordan’s participation in the hearings on the impeachment of President Richard Nixon in 1974 was she made a nationally recognized figure, as it was

2. later in the United States House of Representatives, Barbara Jordan did not become a nationally recognized figure until 1974, when she participated in the hearings on the impeachment of President Richard Nixon, which were

3. later in the Untied States House of Representatives, it was not until 1974 that Barbara Jordan became a nationally recognized figure, with her participation in the hearings on the impeachment of President Richard Nixon, which was

4. then also later in the United States House of Representatives, not until 1974 did Barbara Jordan become a nationally recognized figure, as she participated in the hearings on the impeachment of President Richard Nixon, being
5. then also later in the United States House of Representatives, Barbara Jordan did not become a nationally recognized figure until 1974, when she participated   in the  hearings on the impeachment of President Richard Nixon, which was

答案： B没问题。 也知道which 应该修饰hearings，单数对于D,E前面的 then also later用法不是很明白。觉得怪怪的，但是好像也没什么错，哪位大侠知道then also later的对错及用法的可否告知一下？ 我发现我总是喜欢选怪怪的选项，唉。。。。。。。。

没人理我吗。。。。。。。。。。

temp, thank you very much!