Professor Rashad Is Interested in Studying Cognitive Development

Professor Rashad is interested in studying cognitive development.He collects and compares data from a group of 6-year-olds and a group of 10-year-olds.Five years later,he compares these two groups to each other again as well as to their own performance in the study five years ago.What type of research design is Professor Grant using?

A) cross-sequential design
B) longitudinal design
C) behavior genetics design
D) cross-sectional design