The type of correlational study that observes people on two or more occasions over time is a

A) cross-sectional study.
B) temporal study.
C) case study.
D) longitudinal study.

A longitudinal study observes the same individuals or groups over time, making it the best choice for a study that observes people on two or more occasions over time. Cross-sectional studies compare different groups at a single point in time, temporal studies focus on the timing of events, and case studies focus on a single individual or situation.