How would you form a superlative for the adverb widely?

A. Add the word less
B. Remove the “ly”
C. Add the word most
D. Add the suffix “est”

I think it's D. Is that correct?

Let me see:

He spread the rumor widely.

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He spread the rumor most widely ?

Yes, you are correct. The correct answer is D, adding the suffix "est" to the adverb widely to form the superlative degree. To explain this further, to form the superlative degree of most adverbs, you usually add the suffix "-est" after removing the "ly" ending. So in this case, by adding "-est" to the stem word wide, it becomes widest, making it the superlative form of the adverb widely.