Which of the following best defines epidemiology in the context of public health?

• A. A laboratory-based science that studies only the biological mechanisms of disease in cell cultures, excluding any analyses of distribution, population determinants, or public-health application of findings.
• B. A discipline narrowly focused on identifying the microbe that causes a disease, without considering population-level patterns or prevention strategies beyond causation.
• C. A clinical medical specialty that provides one-to-one patient diagnosis and treatment plans based solely on individual lab results rather than population trends, surveillance data, or prevention programs.
• D. The study of the distribution, patterns, and determinants of health and disease in human populations used to inform disease control and prevention.

Answer: (D)