Salt deposits and moisture threaten to destroy the Mohenjo-Daro excavation in Pakistan, the site of an ancient civilization that flourished at the same time as the civilizations in the Nile delta and the river valleys of the Tigris and Euphrates.

A.that flourished at the same time as the civilizations

B.that had flourished at the same time as had the civilizations

C,that flourished at the same time those had

D.flourishing at the same time as those did

E.flourishing at the same time as those were

当时觉得A里，那个civilizations前面或者后面好像缺少了did来代替省略的flourished，就排除了A，看到B选项as后面补出了had，也忘了考虑时态是不是正确就选了B。后面看解释，说B是错在flourish不应该用过去完成时。但是A这种as后面不补出did的做法是对的么？

还是说选答案选个相对最优的，虽然A和B都有问题，但是B的问题更大，A没有did的问题其实可以接受？