Sentence Correction

Hi All,

In the below question the OA is [spoiler]"E".[/spoiler]. Can someone please help me understand what is wrong with "D" in the below question. how "E" is better then "D" .

There is no consensus on what role, if any, is played by acid rain in slowing the growth or damaging forests in the eastern United States.


(A) slowing the growth or damaging
(B) the damage or the slowing of the growth of
(C) the damage to or the slowness of the growth of
(D) damaged or slowed growth of
(E) damaging or slowing the growth of

damaged or slowed act as an adjective

damaging or slowing the growth, act as a verb,

what role is played by acid rain in ? (verb or adjective),

I just checked dictionary.com.....

As per the site....it says damaging is adjective

but damage can be noun or verb...here in my opinion damaged is the verb form of damage....

Please tell if I am misinterpreting something....