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

A.which amounts to a little less than half the population of the state, down from
nearly three-quarters only a decade ago

B.which amounts to a little less than half the population of the state, down from
a decade ago, when it was nearly three-quarters

C.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

D.amounting to a little less than half the population of the state, down from
nearly three-quarters a decade ago

E.amounting to a little less than half the population of the state, down from
what it was a decade ago by nearly three-quarters

请牛人解释一下各个选项，为什么是d啊。谢谢

個人看法....
About C,
1. that ( does not know what it refers )
2. amounts ( does not parallel to plural S)
3. wrong modify ( a decade ago should follow three-quarters )

D是正确的， down from nearly three-quarters (of the population of the state) a

decade ago.