Mark Shares a Private Practice with Ian

Mark shares a private practice with Ian. They are both clinical psychologists. Mark notices that Ian has been scheduling one particularly attractive female client at the end of the day pretty consistently. One night Mark is working late and sees Ian and this woman holding hands on the way to the parking lot. The first thing Mark should do after observing this ethical violation is

A) notify the APA ethics board.
B) ignore it, as it is not his business or his violation.
C) talk to Mark and discuss the ethical issues.
D) call into a radio show and announce that Mark is not a trustworthy colleague.