Which sentence uses commas correctly? a. ride on over, kelly and take these books to them. b. sir would you show me, the way to the museum? c. wait megan, we'll go to the library together. d. ms. o'rourke is waiting outside, mr. martinez.

C. Wait Megan, we'll go to the library together.

Commas act as sort of a breath in the sentence, you wouldn't need one in A or B. It would be strange to pause there, so it is incorrect. As well, whenever you directly address someone in a sentence you need a comma after their name, however it has to do it without changing the sentence. Therefore C is the correct answer.