Who and which - What to choose when we are referring to a choice between two or more things or persons
I think "Which" is the best interrogative pronoun here. You clearly are asking someone to choose from within a number of choices; and "who" doesn't convey that meaning. When you ask with "Who" the most natural answer would be about the identity of that person.
-Which is your father? -He is the man in white.
-Who is your father? -He is Dr. Peter Smith.
Take a look here. "Who" is never used for asking about choices.