Which word in the sentence is a gerund?

A. pounding

B. blowing

C. driving

D. exciting

I don't know the sentence ... maybe you can post it in the comments?

Because from the options: all of them could be gerund! A gerund is a verb-form that can function as a noun; as a subject in the sentence. For example:;

Driving is my favourite pastime.

so, chose the one that you can substitute (along with any words that come with it; such as "driving cars") with "it" and the sentence would still make sense,