## Core Concept
Secondary prevention involves measures taken to detect and treat problems early before the onset of significant symptoms, thereby preventing further complications. It targets individuals who are asymptomatic but have risk factors or early disease. This approach aims to halt the progression of disease.

## Why the Correct Answer is Right
Secondary prevention includes activities such as screening tests, early detection, and treatment of disease to prevent progression. For example, screening for hypertension, diabetes, and certain cancers; early detection and treatment can significantly alter the disease course. This approach is crucial for diseases where early intervention can make a significant difference in outcomes.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it does not accurately describe secondary prevention. Without specific details on what A entails, we can infer based on the definition of secondary prevention that A likely refers to either primary prevention (preventing disease before it occurs) or tertiary prevention (reducing the impact of an ongoing illness).
- **Option B:** Similarly, this option does not align with the definition of secondary prevention. It might represent a different level of prevention.
- **Option D:** This option is incorrect as it likely represents either primary or tertiary prevention, given the definitions and goals of these prevention levels.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the levels of prevention are hierarchical and sequential:
- **Primary prevention** aims to prevent disease before it occurs (e.g., vaccination, lifestyle modifications).
- **Secondary prevention** seeks to detect and treat disease early (e.g., screening mammography, blood pressure checks).
- **Tertiary prevention** focuses on reducing the impact of an ongoing illness or injury that has lasting effects (e.g., rehabilitation, disease management).

## Correct Answer Line
**Correct Answer: C.**