## **Core Concept**
Behavioural therapy is a type of psychotherapy that focuses on learning's role in developing both normal and abnormal behaviors. It assumes that behavior is either learned or unlearned and thus, the therapeutic approach involves reinforcing desired behaviors and eliminating undesired ones.

## **Why the Correct Answer is Right**
John B. Watson and B.F. Skinner are often associated with the development of behavioral therapy through their work in behaviorism. However, the specific credit for introducing behavioral therapy as a distinct therapeutic approach goes to **John B. Watson** and his work laid the foundation for **B.F. Skinner**'s operant conditioning. Yet, among the given options, if we consider the key figures, **B.F. Skinner** is notably recognized for his work in operant conditioning which is a fundamental concept in behavioral therapy.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While several psychologists contributed to psychology, without the specific name, it's hard to assess its accuracy directly in relation to behavioral therapy.
- **Option B:** Similarly, without a specific name, it's challenging to evaluate its correctness.
- **Option C:** This could potentially be a correct figure if it aligns with known contributors to behavioral therapy, but without specifics, it's hard to validate.

## **Clinical Pearl / High-Yield Fact**
A key concept in behavioral therapy is **classical conditioning**, discovered by Ivan Pavlov, and **operant conditioning**, studied by B.F. Skinner. Behavioral therapy techniques are widely used to treat anxiety disorders, phobias, and other mental health conditions.

## **Correct Answer:** D. B.F. Skinner