Observational studies differ from experimental studies in that:(CIRCLE ALL THAT APPLY):(3 points)

A.Observational studies include cohort studies

B.In observational studies, the researcher decides which participants get the exposure.

C.In observational studies you cannot have an a prior hypothesis

D.For exposures known to be harmful, observational studies are often the more ethical choice.

E.Observational studies include randomized control trials