## **Core Concept**
The question tests understanding of risk factors for Coronary Heart Disease (CHD), specifically distinguishing between modifiable and non-modifiable (or fixed) risk factors. CHD risk factors can be broadly categorized into those that can be changed (modifiable) and those that cannot (non-modifiable).

## **Why the Correct Answer is Right**
Non-modifiable risk factors for CHD include age, sex, and family history of early coronary heart disease. Among these, **family history** is a significant non-modifiable risk factor because it encompasses genetic predispositions that cannot be altered. A positive family history, especially if a first-degree relative (parent or sibling) had CHD before the age of 55, increases an individual's risk.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While certain dietary habits and physical inactivity are modifiable risk factors, without specific details, it's hard to directly refute this option. However, typically, dietary factors are considered modifiable.
- **Option B:** This option is too vague without context but often, hypertension (high blood pressure) is a modifiable risk factor through lifestyle changes and medication.
- **Option C:** Smoking is a well-known modifiable risk factor for CHD. Quitting smoking significantly reduces the risk of developing coronary heart disease.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that while non-modifiable risk factors like family history and age cannot be changed, being aware of them can help in early detection and management of modifiable risk factors. For instance, individuals with a strong family history of CHD might start screening for risk factors earlier.

## **Correct Answer:** . Family History