问一道gwd 两次出现答案不同

Several financial officers of the company spoke on condition that they not be named in the press reports.

1. that they not be named
2. that their names will not be used
3. that their names are not used
4. of not having their names
5. of not naming them

这道题两次给的答案不一样 一次是a一次是c

改选哪个呢？ b为什么错呢？

我觉得是a，虚拟语气，省略了if，呵呵 on condition that (if) they...

b的时态部队，前面是spoke的：）

谢谢！