Which of the following contains a vague pronoun reference?
A. According to Zoe, Willie Mays hit 660 career home runs, although Joe DiMaggio had a higher batting average. She said that he is her favorite player.
B. According to Zoe, Willie Mays hit 660 career home runs, although Joe DiMaggio had a higher batting average. She said that Mays is her favorite player.
Determine the correct option from the provided choices and reply with its corresponding letter.

A