It is well known in the supermarket industry that how items are placed on shelves and the frequency of inventory turnovers can be crucial to profits.


(A) the frequency of inventory turnovers can be
(B) the frequency of inventory turnovers is often
(C) the frequency with which the inventory turns over is often
(D) how frequently is the inventory turned over are often
(E) how frequently the inventory turns over can be

OA: E

Could somebody explain why is E a better choice than D? D has 'is' before inventory. E is in passive voice (while the first clause is in active voice). How is E better in terms of parallelism than D?

Now look at the following question

In recent years cattle breeders have increasingly used crossbreeding, in part that their steers should acquire certain characteristics and partly because crossbreeding is said to provide hybrid vigor.
(A) in part that their steers should acquire certain characteristics
(B) in part for the acquisition of certain characteristics in their steers
(C) partly because of their steers acquiring certain characteristics
(D) partly because certain characteristics should be acquired by their steers
(E) partly to acquire certain characteristics in their steers

Here the OA is E and D is eliminated just because it uses passive voice. I just don't get it. The second part does not use infinitive in the main clause. So. why is E a better choice than D?