Answer:
What is your girlfriend's name, Mary Ann?
Step-by-step explanation:
In this statement, the girlfriend is showing ownership of her name, so we need to use a 's, so that word would be girlfriend's.
Second, the question is being asked directly to Mary Ann. To show this, we need to put a comma before her name to allow a natural pause in the sentence and to show the reader that the statement is being said to Mary Ann.
Finally, the statement is a question. To show this, we just need to add a question mark to the end.
Your final sentence should say, "What is your girlfriend's name, Mary Ann?"