**Core Concept**
Chemoprophylaxis refers to the administration of a medication to prevent or reduce the risk of disease development. This concept falls under the broader category of primary prevention, which aims to prevent disease before it occurs.

**Why the Correct Answer is Right**
Primary prevention targets individuals or populations that are at risk of developing a disease or condition. Chemoprophylaxis, such as administering antibiotics to prevent meningococcal meningitis in close contacts of a patient, is a classic example of primary prevention. By administering a medication, we reduce the risk of disease onset, thereby preventing the occurrence of the disease. This approach is distinct from secondary prevention, which focuses on early detection and treatment of diseases, and tertiary prevention, which aims to reduce the impact of an ongoing illness that has lasting effects.

**Why Each Wrong Option is Incorrect**
**Option A:** Primordial prevention refers to actions taken to prevent the emergence or development of risk factors in the first place, such as reducing tobacco use or promoting a healthy diet. Chemoprophylaxis is not a form of primordial prevention.
**Option C:** Secondary prevention involves early detection and treatment of diseases, often through screening or surveillance. Chemoprophylaxis, while aiming to prevent disease, does not involve early detection or treatment.
**Option D:** Tertiary prevention focuses on reducing the impact of an ongoing illness that has lasting effects, such as managing chronic conditions. Chemoprophylaxis is not a form of tertiary prevention.

**Clinical Pearl / High-Yield Fact**
Remember the hierarchy of prevention: Primordial prevention > Primary prevention > Secondary prevention > Tertiary prevention. This framework helps healthcare professionals and students understand the different levels of prevention and their distinct goals.

**Correct Answer:** ✓ Correct Answer: B. Primary prevention.