Final answer:
John B. Watson and B.F. Skinner were pivotal in the development of the behaviorist approach to psychology, which emphasizes the study of observable behavior and its environmental determinants over internal mental processes. The correct answer is (d) Behaviorist.
Step-by-step explanation:
The answer to the student's question is (d) Behaviorist:
Pioneering psychologists such as John B. Watson and B.F. Skinner were instrumental in developing the behaviorist approach to psychology. Their work laid the groundwork for understanding behavior through the lens of learning and external reinforcement, rather than internal mental states.
Watson, often heralded as the father of behaviorism, pushed for a focus on observable behavior, distancing psychology from the unobservable mental processes. Skinner further expanded on behaviorism by elaborating on the principles of operant conditioning, demonstrating how behavior is shaped by its consequences. Their collective efforts established behaviorism as a dominant force in early 20th century psychology. This approach advocates that behavior can be explained and predicted by environmental factors, without the need to speculate about mental states, reflecting a significant shift from earlier psychological theories.