When Billy is quiet and respectful in church, he is rewarded with a trip to McDonald's after church. In church today, BIlly misbehaved quite a bit, leading his mother to say "OK, Billy. Since we've asked you to behave so many times today and you haven't been willing to do it, we're just going to go home after church today. No McDonald's." This is an example of _____
1) Negative reinforcement
2) Response cost
3) Omission training
4) Punishment