SC-need clear explaination

[ngotrung]

In 1990’s, there are more babies born by women over thirty years old than under it.

(A) than under it

(B) than were they under it

(C) than had been under it

(D) than were the babies

(E) than those were under it

[Trang]

Going down to A and E.

Eliminate E since "those" referes to either the babies or the women. In addition, if it indicates the women, it'd be better structure: ... by women over thirty years old than by those who were under it.

A is not absolutly right, but it's the best in this case

[Son]

Another vote for A.
Đồng ý với giải thích của chị Trang. :D

[Longatum]

??? câu A có gì mà không phải là "absolutely right" chẳng qua nó tắt lại của than by those under it thôi.

[Trang]

Tớ mean cái cách nó viết tắt câu so sánh và cách dùng it ở đây. It refers to cả cụm "thirty years old", điều ít thấy trong gmat land thôi :)