What is a cross-sectional study? choose the correct answer below. a. cross-sectional studies are observational studies that are retrospective, meaning that they require individuals to look back in time or require the researcher to look at existing records. b. cross-sectional studies are a list of all individuals in a population along with certain characteristics of each individual. c. cross-sectional studies are observational studies that collect information about individuals at a specific point in time or over a very short period of time. d. cross-sectional studies first identify a group of individuals to participate in the study. these individuals are then observed over a period of time. over this period of time, characteristics about the individual are recorded