An Investigator Who Studies the Development of Aggression by Selecting

An investigator who studies the development of aggression by selecting a sample of 2-year-olds and a sample of 4-year-olds and follows them for 5 years to see if they become any more or less aggressive is employing a _____.

A) cross-sectional design
B) cross-cultural design
C) longitudinal design
D) sequential design