Answer:
The correct answer is letter "B": positive reinforcement.
Step-by-step explanation:
American psychologist B.F. Skinner (1904-1990) proposed the Operant Conditioning theory to describe the process by which individuals learn influenced by rewards and punishments. The theory establishes a direct relationship between behavior and the consequences of that behavior.
Skinner described positive reinforcement to the fact of providing a reward to an individual after a given behavior. The individual is likely to repeat the same behavior with the expectation of receiving the reward constantly. In such a way the reward represents the reinforcement stimulus.
Thus, the bonus check Peggy's boss gave her is a stimulus given to motivate her to continue working hard.