Sentence Correction

By 1918, advances in tractor technology had led to increased yield, efficiency of labor, profit per square acre, and reduced the amount of time in which fields were planted.


A:profit per square acre, and reduced the amount of time

B:profit per square acre, and had reduced the amount of time

C:profit per square acre, and a reduction in the amount of time

D:and profit per square acre, but the amount of time was reduced

E:and profit per square acre while reducing the amount of time


OA : E

Am not able to figure out why D is wrong.
Please explain.

Thanks.
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