Subjects are classified according to their exposure to a factor of interest and then are observed over time to document the incidence of disease in what type of study? cross-sectional study retrospective cohort study case-control study prospective cohort study

I believe the answer is: prospective cohort study
prospective cohort study is a form of longintudinal study that include several subjects with similar characteristics.
After gathering the subject, we would give them different exposures in order to know the differences that the exposures would create toward the similar subjects

Sheet stain on pee wee's sheets

The will be a : great britain wanted french gold mines