I think it's slightly idiomatic (people just wouldn't say the sentence that way) as well as the fact that if possible, you should avoid gerunds.
That's not to say they will never be the correct answer - they likely will be in some cases. But if there is an answer choice that corrects the errors in the sentence and does not use gerunds, it's probably better.
Make sure when you do use a gerund that it's preceded with a possessive noun or pronoun, ie
"His condemning of racial injustice in "Letter from a Birmingham Jail" ..."
would be technically correct, but
"His condemnation of racial injustice..."
would be better if it was a choice.
In short, usually if you see a gerund, there's a better noun to use. Gerunds aren't always technically incorrect (in this case they are because the nouns they refer to are not possessive) but if the choice is between a correct gerund and a noun, pick the noun for stylistic reasons.
