<prompt> Of the different epidemiological study designs available to test the association between risk factor and disease, the best design is of -Case-control studyEcological studyCohort studyCross-sectional study  <response>: Ans. is c i.e., Cohort study Comparison of various epidemiological EcologicalCross sectionalCase controlCohortProbability of selection biasNAMediumHighLowRecall biasNAHighHighLowLoss to follow upNANALowHighConfoundingHighMediumMediumLowTime required.LowMediumMediumHigh. CostLowMediumMediumHighStrength of causal interferenceLowLowMediumHigh 