Final answer:
Sigmund Freud was not instrumental in contributing to the Cognitive-Behavioral Model; his work pertained to psychoanalytic theory. Albert Ellis, Aaron Beck, and John B. Watson's works all contributed to the foundations of cognitive and behavioral psychology, which are integral to the Cognitive-Behavioral approach.
Step-by-step explanation:
The theorist among the options provided who was not instrumental in contributing to the Cognitive-Behavioral Model is B: Sigmund Freud. Albert Ellis, Aaron Beck, and John B. Watson were all significant contributors to cognitive and behavioral psychology, which underpin the Cognitive-Behavioral Model.
Sigmund Freud, however, is known for developing psychoanalytic theory, which focuses on the unconscious mind and its influence on human behavior. In contrast, Albert Ellis developed Rational Emotive Behavior Therapy (REBT), Aaron Beck is known for his work in Cognitive Therapy (CT), and John B.
Watson is considered one of the fathers of behaviorism, which emphasizes the study of observable behavior. Cognitive-Behavioral Therapy (CBT) combines cognitive and behavioral approaches to address psychological issues, and Sigmund Freud's work does not align with the principles of CBT.