compare

[sq720]

the census bureau reports that more than three-fifths of all married couples in the united states now have two incomes, significantly more than earlier decades did
A.) earlier decades did
B.) earlier decades
C.) in earlier decades
D.) earlier decades have
E.) that in earlier decades

C

I can cancel A and b can't compare illogical comparisons
I am not sure why D and E are incorrect

[axat]

Here's one way of looking at it:

In D, it uses 'have' which is present tense-ish. Or you could say that this choice says that the couples have more income than the decades. Decades can't have an income.

And E is more wordy than C.

This probably is convoluted logic, but it works for me, and it might just work for you.