**Question:** The commonly used theory to predict individual's behaviour regarding preventive health care is:

A. Health Belief Model
B. Social Cognitive Theory
C. Theory of Planned Behavior
D. Transtheoretical Model

**Correct Answer:** **C. Theory of Planned Behavior**

**Core Concept:** The Theory of Planned Behavior (TPB) is a psychological theory that aims to explain how individuals make decisions about engaging in health-related behaviors, including preventive health care. It builds upon Ajzen's earlier work on the Theory of Reasoned Action (TRA).

**Why the Correct Answer is Right:** The TPB is based on the premise that an individual's intention to perform a behavior (in this case, seeking preventive health care) is determined by three main constructs: Attitude towards the behavior, subjective norm, and perceived behavioral control.

1. **Attitude towards the behavior:** This refers to an individual's positive or negative evaluation of the behavior. In the context of preventive health care, a positive attitude towards the behavior would lead to a higher likelihood of engaging in preventive health practices.
2. **Subjective norm:** This is the perception of social pressure to engage or not engage in the behavior. A strong subjective norm can influence an individual's decision to seek preventive health care.
3. **Perceived behavioral control:** This refers to an individual's perception of their ability to engage in the behavior. A strong perceived behavioral control suggests that an individual is more likely to seek preventive health care.

**Why Each Wrong Option is Incorrect:**

A. Health Belief Model (HBM) is a different theory that focuses on predicting an individual's health-related behaviors based on the perceived benefits and barriers of the behavior, as well as cues to action. While both HBM and TPB consider individual attitudes and subjective norms, HBM focuses more on perceived benefits and barriers, while TPB incorporates perceived behavioral control.

B. Social Cognitive Theory (SCT) is another theory that focuses on the interplay between an individual's thoughts, feelings, and behavior. While SCT provides insights into how personal factors influence behavior, TPB is specifically designed to explain how attitudes, subjective norms, and perceived behavioral control interact to influence behavior.

C. Theory of Reasoned Action (TRA) is closely related to TPB, as both are based on the same core principle: the intention to perform a behavior determines the behavior itself. However, TPB extends TRA by incorporating perceived behavioral control.

D. Transtheoretical Model (TTM) focuses on the process of behavior change, particularly in the context of quitting smoking or adopting healthy lifestyles. While TTM is useful for understanding behavior change, it is not primarily used for predicting preventive health care behaviors like the TPB.

**Clinical Pearl:** In healthcare settings, understanding and applying TPB can help healthcare professionals guide patients to adopt preventive health care practices, as it provides insight into how an individual's thoughts, feelings, and social influences interact to shape their intention to engage in preventive health behaviors, which ultimately impacts health-related behaviors.