Which statement accurately describes the difference between cross-sectional and longitudinal study designs?

• A. Cross-sectional follows the same individuals over time; longitudinal assesses a population at one time.
• B. Cross-sectional assesses a population at a single time point; longitudinal follows the same individuals over multiple time points.
• C. Cross-sectional is an experimental design; longitudinal is a case study.
• D. Both designs track changes in individuals over time.

Answer: (B)