An influential economic thinker, known as "the father of modern economics,” was John Keynes.
Milton Friedman.
Friedrich Hayek.
Adam Smith.

the answer to the question is punishment. or more specifically, positive punishment.

positive punishment occurs when a behavior is given a negative consequence for the individual doing the behavior.

sara no longer wants to ask questions (the behavior) because she is ridiculed by mr. smith (the punishment).

reinforcement is inaccurate because reinforcement always gives positive consequences for the individual doing the behavior, be it by introducing a pleasant consequence or removing an unpleasant one.