They went with the option to the left side, to Hall. Might not have been much of an "option" though -- looked like it was going to be pitched to Hall from the get-go. He got a yard, maybe a yard and a half, but Cal was waiting for him (thank God!). Close enough to make my heart race though.
The crazy thing is, AF even called a time out before the play (after the TD) -- so the coach had plenty of time to consider the call. So it's not like this was a knee-jerk reaction under time pressure, where he might have made the wrong call. This was deliberate; he wanted the two points. He wanted to cover.