请教：句子+which do 和 句子+doing的区别

Q23:

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 there-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

这个语法点我有点糊涂，找了一道GWD题做例子，如题，我想知道which amounts和amounting在用法和意思上的区别？

amounting修饰的是什么？如果换成which amounts又是修饰什么？

多谢！

amounting是伴随，表示前面的动作带来的结果。

which是就近修饰california.

但是which不是可以指代前面整个句子吗？