This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': 'In a case-control study of a suspected association between breast cancer and the contraceptive pill, all of the following are true statements except \nSelect and explain. \nA. The control should come from a population that has the same potential for breast cancer as the cases, B. The control should exclude women known to be taking the pill at the time of the survey, C. All the controls need to be healthy, D. The attributing risk of breast cancer resulting from the pill may be directly measured', 'role': 'user'}, {'content': "Answer: D \nExplanation: The attributable risk of breast cancer resulting from the pill may be directly measured. AR calculation requires incidence which can be obtained from only a coho study. Reference: Park's textbook of preventive and social medicine, 23rd edition, page no:78", 'role': 'assistant'}]