Jacob brings his three-year-old daughter in for a research study on how children from age 3 to 5 develop understanding of numbers. He is told that his child will either be assigned to an experimental or control group and that he will need to bring her back to the lab every six months for the next two years. Which type of study is Jacob's daughter participating in?A) CorrelationalB) Cross-sectionalC) DescriptiveD) Longitudinal