The branch of science that investigates when and how diseases occur in populations is called?

• A. Epidemiology
• B. Pathology
• C. Physiology
• D. Biostatistics

Answer: (A)

This question targets understanding of epidemiology, the branch that investigates when and how diseases occur in populations. Epidemiology studies patterns of disease across groups—who is affected, where they are, and when cases arise—to identify risk factors, track outbreaks, and measure public health impact. It uses concepts like incidence (new cases) and prevalence (total cases) to describe disease frequency over time and across populations. This focus on population-level patterns and determinants sets it apart from pathology, which looks at disease changes in tissues and cells; physiology, which examines how bodily systems function; and biostatistics, which provides the data-analysis tools used in many fields, including epidemiology.