The essential truth about B.F.Skinner's research is that

A) it is more similar to Adler's than Freud's.
B) it relies on factor analysis.
C) it is based on clinical studies of neurotics.
D) his study of behavior is the antithesis of the psychoanalytic, trait, life span, cognitive and humanistic approaches.

B.F. Skinner's research on behavior is fundamentally different from traditional psychological approaches such as psychoanalytic, trait, life span, cognitive, and humanistic approaches. Skinner believed that behavior can be explained by external factors such as rewards and punishments, rather than internal motives or personality traits. He conducted experiments on animals and humans to study the impact of reinforcement and punishment on behavior. Therefore, option D correctly summarizes the essential truth about Skinner's research.