Ecently, your employee greg has developed the annoying habit of chatting with you while you are trying to work. you want greg to stop this, so when he comes into your office, you don't look up, and when he talks to you, you don't respond. in reinforcement theory terms, you are using to modify greg's behavior.

I believe the answer is: Extinction

In psychology, Extinction refers to the situation when a behavior is discouraged by not giving it any reinforcement.
By ignoring the employee, Greg prevent the employee from having the expected reward (in this case, the reward is Greg's attention) and this would make the employee stop annoying greg and seek the reward toward another person.

Sometimes but itt depends, their is a lot if drugs on campus too so you really can't just say that