Even though there is a short explanation to this question in the list, it is not quite clear. Could you tell me why not to choose A but E.
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.
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 | 
