<prompt> To test the association between risk factors and disease, which of the following is the weakest study design?Case control studyEcological studyCoho studyCross-sectional study  <response>: Ecological studies, as they donot take into consideration individual data of exposure diseases, have poorest evidence of determining association. Hence they are considered as weak studies. These are done at point of time commonly used in nutritional surveys. Order from strong to weak study determining association:Randomized Control Trial Retrospective Coho Study Prospective Coho Study Case control study Cross sectional study Ecological study. 