Mr Lynch Always Uses His "Mean" Face to Stop Undesirable

Multiple Choice

Mr. Lynch always uses his "mean" face to stop undesirable behaviour in his first-period class. However, even though he looks at Tommy with his mean face each time Tommy talks out of turn, Tommy is talking out of turn more and more frequently. For Tommy, the mean face is apparently a

A) cue.
B) model.
C) negative reinforcer.
D) positive reinforcer.