A researcher wants to see how video game violence affects children. He finds participants in one of five age groups: 6,9,12,15, and 18. Each participant provides the number of hours they play violent videos in a week. The researcher measures how aggressive they are in response to an insult. What kind of design did the researcher use?
O Cross sectional design
O Single strata design
O Cross-generational design
O The cohort sequential design
O Longitudinal design