Which best describes a prevalence survey?

• A. A cross-sectional design that measures prevalence of disease and risk factors in a defined population.
• B. A longitudinal design following participants over time to assess incidence.
• C. A randomized controlled trial comparing interventions.
• D. A qualitative study exploring perceptions.

Answer: (A)

A prevalence survey is a cross-sectional assessment that estimates how common a disease and related risk factors are in a defined population at a specific time. It captures the proportion of people with the disease in that snapshot, and can collect exposure data simultaneously. This differs from incidence, which requires following people over time to identify new cases. A randomized controlled trial compares interventions, not prevalence, and a qualitative study focuses on perceptions rather than numerical prevalence. Therefore, describing it as a cross-sectional design that measures prevalence of disease and risk factors in a defined population best fits a prevalence survey.