Children in Industrialized Societies Tend to Show Remarkable Changes in How

Children in industrialized societies tend to show remarkable changes in how they reason about the world around the same time that they begin school. The most effective and practical way to disentangle the effects of schooling from that of other developmental factors would be to:

A) randomly assign children of a single culture to begin school at different ages.
B) conduct a correlational study that includes measures of cognitive development, school achievement, and age at which the child began school.
C) investigate the issue in different cultures where the age at which children begin school varies.
D) conduct idiographic research.