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This question assesses 3 different case-control studies, described below. Rank these three studies in order of their (increasing) risk of a survival (or incidence-prevalence) bias. Therefore, the first study in the rank order you choose should be the one with the lowest risk of a survival bias, and the third study in the rank order you choose is the one with the highest risk of such a bias. Study #1 assesses smoking as a risk factor for pancreatic cancer (which has a 5-year survival of 12%), and enrolls incident cases. Study #2 assesses sun exposure as a risk factor for basal cell skin cancer (which has a 5-year survival of 85%), and enrolls prevalent cases. Study #3 assesses betel nut chewing as a risk factor for esophageal cancer (which has a 5-year survival of 22% ), and enrolls prevalent cases. Answer: The appropriate rank order is: A. B Cc. D #3