<prompt> Best epidemiological study is -RCTMeta-analysisCohort studyCase-control study  <response>: Ans, is b i.e., Meta-analysis o Here are the different epidemiological studies with decreasing order of accuracy to test the association between risk factor and diseaseSystematic review and meta-analysis - Overall most reliableRandomized controlled trials controlled clinical trails - Most reliable individual study.Retrospective Non-concurrenthistoric Cohort study.Prospective concurrent Cohort study.Case control studyCross-sectional studyEcological study 