Top managers are often stymied by the ______________________________ conflict.

(I) difficulties of managing

(II) difficulty for managing

(III) management of difficult

“difficulties of managing” is the correct phrase to make the sentence grammatically correct. In the context of the correct grammar usage in the sentence, “of” is the correct preposition. However, the phrases (II) and (III) make no relevance to the actual meaning of the sentence. Hence 1 is the correct option.