请教GWD14-Q16,这类题目怎么判断？

Q16:

Soaring television costs accounted for more than half the spending in the presidential campaign of 1992, a greater proportion than it was in any previous election.

1. a greater proportion than it was
2. a greater proportion than
3. a greater proportion than they have been
4. which is greater than was so
5. which is greater than it has been

答案是B,但我觉得是A。

将句子补充完全不应该是 more than half the spending in the presidential campaign of 1992 is a greater proportion than it was in any previous election. 用it 指代the proportion of spending.

这类题目，总是弄不清楚，请高手们指导啊。

A是不正確的。

it後面不用接was(前句並沒有用be動詞去形容more than half the spending )

我的想法中全句表達應該是：

Soaring television costs accounted for more than half the spending in the presidential campaign of 1992,a greater proportion than( the proportion of spending )in any previous election.

括號中省略，故選B