## Core Concept
The question targets the most effective strategy for reducing mortality from Coronary Heart Disease (CHD) at a population level. It involves understanding preventive cardiology and public health strategies.

## Why the Correct Answer is Right
The correct answer, **Population Strategy**, focuses on changing the overall risk profile of the population rather than targeting high-risk individuals. This approach involves public health measures such as promoting a healthy diet, increasing physical activity, reducing smoking, and implementing policies to decrease salt intake and increase consumption of fruits and vegetables. By shifting the risk curve to the left, even small reductions in risk can lead to significant decreases in CHD mortality across the population.

## Why Each Wrong Option is Incorrect
- **Option A: High-Risk Strategy** - This approach targets individuals with high levels of risk factors. While effective for those individuals, it may not have as significant an impact on overall population mortality as a population strategy.
- **Option B: Secondary Prevention** - This involves preventing further disease progression in individuals who already have CHD. It's crucial but doesn't address the primary prevention of CHD in the broader population.
- **Option C: Tertiary Prevention** - Focuses on reducing the impact of an ongoing illness that has lasting effects. This is also important but not directly aimed at reducing CHD mortality at a population level.

## Clinical Pearl / High-Yield Fact
A key concept in preventive cardiology is the **"10% Rule"**, suggesting that a 10% reduction in CHD risk factors can lead to a 20-30% reduction in CHD events. Population strategies aim to achieve such reductions through widespread lifestyle and environmental changes.

## Correct Answer Line
**Correct Answer: D. Population Strategy**