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. Professor Grant is employing a ________ design in his research.
◦ cross-sequential
◦ longitudinal
◦ behavior genetics
◦ cross-sectional