Question

Which sentence uses the superlative form of an adverb? A. He spoke most persuasively of all the candidates. B. I sometimes walk to the grocery store. C. My brother's baseball team scored more runs than my team. D. Huge turtles swam slowly through the water.

Answer 1

Superlative adverb means to compare three or more people, places, or things. It's used to state that the action performed is to the highest degree within a group or of its kind.  therefore the answer is a 

Answer 2

Superlative form means the most of the others then it is answer A