Answer:A cross-sectional study
Explanation:A cross-sectional study is a study in which a researcher gathers data at a particular point in time.
The subjects are chosen based on specific variables of interest.
Cross-sectional studies are mostly used in developmental psychology, but can also be used in education and social science.
For example,a researcher may study developmental psychology by choosing people from various age group and study them at one point in time. This is done so that any apparent differences can be considered to have been caused by the differences in age.
Cross-sectional study is an observational study which is descriptive but doesn't necessarily explain the cause of what is being observed. are observational in nature and are known as descriptive