Simon presents with alopecia areata with well-circumscribed patches of hair loss on the crown of his head. How do you respond when he asks you the cause?

a. “You must be under a lot of stress lately.”
b. “It is hereditary. Did your father experience this also?”
c. “The cause is unknown, but we suspect it is due to an immunologic mechanism.”
d. “We’ll have to do some tests.”