Final answer:
B.F. Skinner would classify Brody earning $20 for each A as positive reinforcement, as it is an addition of a desirable stimulus to increase a behavior.
Step-by-step explanation:
Behaviorist B.F. Skinner would most likely describe Brody earning $20 each time he earns an A in a course as positive reinforcement. In operant conditioning, positive reinforcement is a method used to increase a behavior by adding a desirable stimulus after the behavior occurs. Therefore, when Brody receives $20 for each A, it acts as a reinforcement for his achievement, encouraging him to maintain or increase his effort in academic performances. This concept aligns with Skinner's advocacy of using operant conditioning principles to influence students' behavior in educational settings.