**Core Concept**
Primary prevention refers to interventions aimed at preventing the occurrence of a disease or injury. This level of prevention targets healthy individuals or populations to prevent the development of a disease or condition. It involves measures such as health education, vaccination, and lifestyle modifications to reduce the risk of disease.

**Why the Correct Answer is Right**
The options listed are all examples of primary prevention strategies. Vaccination (A) is a primary prevention measure that aims to prevent the occurrence of infectious diseases. Health education (B) is another primary prevention strategy that empowers individuals to make informed choices about their health. Screening tests (C) can be considered a form of primary prevention for certain diseases, as they aim to detect and prevent the progression of disease.

**Why Each Wrong Option is Incorrect**
**Option D:** Screening tests can be considered a secondary level of prevention, as they aim to detect and prevent the progression of disease in individuals who are already asymptomatic.

**Clinical Pearl / High-Yield Fact**
It is essential to understand the different levels of prevention to provide effective and timely interventions to patients. Remember the mnemonic "PPPS" to recall the levels of prevention: P - Primary (preventing disease occurrence), P - Primary (preventing disease progression), S - Secondary (detecting and treating disease early), and T - Tertiary (managing disease complications).

**Correct Answer:** D. Screening tests can be considered a secondary level of prevention, as they aim to detect and prevent the progression of disease in individuals who are already asymptomatic.