[jrz1972]

Bet/call obviously sucks. You are crushed by anything that raises the river, so that line is out.

The problem with check/call is that when villain bets this river, he is not bluffing. There were no obvious draws on the flop for villain to be chasing, so the fact that he called the flop and turn suggests that he caught some piece of the board. By checking, you allow villain the option of checking down with a 5, but he's obviously betting a Q. So check/call costs the same as bet/fold when you're behind but will often miss a bet when you're ahead.

Thus, we bet/fold. This gets value off a villian that is calling down with bottom pair, 33, A-high or somesuch, and we can be super-confident in folding to a raise.