The most obvious answer after reading the sentence seems to be A, but it is not the right answer, now the question is Why, as "enabling" seems to be correctly modifying the modified action "lead" and the noun "moisture and dampness" seems to be correctly doing the enabling part, but here is the catch there is "
no comma" after humus because of that enabling is now modiying humus which is very very very very wrong :shocked
Now Why D is correct because the relative pronoun "that" is correctly pointing to hummus saying it is the Hummus my lord which is enabling these mushrooms to flourish

rohan2345
Accentuated by the cold weather during rainy season, moisture and dampness in soil lead to decomposition of organic matter into humus enabling mushrooms to flourish.
A. enabling mushrooms to flourish.
B. for the mushrooms to flourish.
C. for flourishing mushrooms.
D. that enable the mushrooms to flourish.
E. that the mushrooms can flourish.
I rejected D because humus seems to be singular and the verb ,enable, is plural. Enlighten me please.
Thanks.
somebody please clear this doubt, why is the verb 'enable' rather than 'enables' ?is humus plural?