GMAT Sentence Correction (SC) | The health benefits of tea have been the subject of much

A B and C are out for SV errors.

For D and E
D. besides thepossible preventing and inhibiting of
E. besidespossibly preventing or inhibiting

Possible is used in D and possibly in E. Possible is an adjective and adjectives can only modify nouns.
also,"the preventing of" and"the inhibiting of" could have been considered nouns only if the equivalent action nouns did not exist.
But sinceprevention andinhibition exist, they are not nouns and therefore cannot be modified
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