可以帮我看看这道题吗？

 Q33:

For the first time in the modern era,
non-Hispanic Whites are officially a minority in California, which amounts to a little
less than half the population of the state, down from nearly three-quarters
only a decade ago.

1. which
        amounts to a little less than half the population of the state, down from
        nearly three-quarters only a decade ago
2. which
        amounts to a little less than half the population of the state, down from
        a decade ago, when it was nearly three-quarters
3. and that
        amounts to a little less than half the population of the state, down from
        a decade ago, when they were nearly three-quarters
4. amounting
        to a little less than half the population of the state, down from nearly
        three-quarters a decade ago
5. amounting to a little less than half the population of the state, down
        from what it was a decade ago by nearly three-quarters

E首先是结构复杂,没有D简单

而且E中的it到底指代什么呢?

it我想楼主觉得是人数的意思,但是人数这个概念句子中没有出现,所以it就不能指代这个虚构的概念

状语吧...说non-hispanic whites的数量是十年前的3/4