Which sentence uses commas correctly?

A.

Ms. O'Hara is not available right now, Mr. Johnson.

B.

Sir can you tell me, the time?

C.

Walk right up there, Allison and tell them what you think.

D.

Hurry Tony, you'll be late for the club meeting!

A or D

The sentence that used comma correctly is, option A. Ms. O'hara is not available right now, Mr. Johnson. You use a comma when you directly address a name of a person or a title in the sentence. This is to emphasize that your message is for that person.