Answer: D. No change needs to be made to this sentence
Explanation:
An adverb is a word that used to modify an adjective or a verb. In this case, the adverb in the question is thankfully.
The sentence given is "Thankfully, my hard work paid off". To use the adverb as a sentence opener, " Thankfully" needs to be the word at the beginning. Since it's already the sentence opener, therefore there's no change to be made.
