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.

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