The correct answer is "Negative reinforcement."
Yelling at Michele's disruptive behavior, which resulted in Michele's disruption stopping, is an example of Negative reinforcement to the teacher's yelling.
The teacher has noticed that Michele's disruptive behavior changes when she yells back at Michele. Although it is not the best alternative, negative reinforcement is paying dividends in the case of Michele.
It was Dr. B.F. Skinnne, who developed the concept of negative reinforcement when established his theory of operant conditioning.