## **Core Concept**
The question pertains to the field of Preventive and Social Medicine (PSM) and its application of behavioural sciences. Behavioural sciences are crucial in understanding and influencing health-related behaviours in populations.

## **Why the Correct Answer is Right**
The correct answer, **C. Social and Behavioural Sciences**, is right because these sciences provide a framework for understanding human behaviour, social influences, and the psychological factors that affect health and disease prevention. They are extensively used in PSM to develop interventions aimed at promoting healthy behaviours and preventing diseases.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although psychology is a part of behavioural sciences, it is not specified as the answer that encompasses the broad application in PSM.
- **Option B:** This option is incorrect as it does not accurately represent the field of study primarily used in PSM.
- **Option D:** This option is incorrect because it does not specifically relate to the behavioural aspect that is crucial in PSM.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **Social and Behavioural Sciences** play a pivotal role in epidemiology and health promotion. Understanding these sciences helps in designing effective public health interventions. A classic example is the Health Belief Model, which is used to predict and explain health behaviours.

## **Correct Answer:** C. Social and Behavioural Sciences