## **Core Concept**
The question tests understanding of behavioural therapy techniques, specifically those based on learning theory and operant conditioning. **Operant conditioning** is a method of learning that employs rewards and punishments for behaviour.

## **Why the Correct Answer is Right**
The correct answer, **Operant Conditioning**, is right because it specifically involves changing behaviour based on its consequences, such as rewards or punishments. In operant conditioning, a **response** (behaviour) is followed by a **reinforcer** (a consequence that increases the likelihood of the behaviour occurring again). This technique is used in behaviour therapy to increase desired behaviours or decrease undesired ones.

## **Why Each Wrong Option is Incorrect**
- **Option A: Classical Conditioning** is incorrect because it involves associating an involuntary response with a stimulus, not using a response as a reinforcer. It was famously demonstrated by Ivan Pavlov's experiments with dogs.
- **Option B: Social Learning Theory** is incorrect because, while it does involve learning behaviours by observing and imitating others, it doesn't specifically focus on using responses as reinforcers.
- **Option C: Cognitive Restructuring** is incorrect because it is a technique used to change maladaptive thoughts, not behaviours directly, and does not inherently involve the use of reinforcers.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **operant conditioning** can be effectively used in a variety of settings, including therapy and education, to modify behaviours by controlling their consequences. A classic example is the use of token economies in psychiatric hospitals to encourage positive behaviours.

## **Correct Answer:** D. Operant Conditioning.