This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Classification, Coho Study, Subject name: Social & Preventive Medicine
[{'content': 'Framingham hea study (CHD study) is a type of: \nSelect and explain. \nA. Coho study, B. Case control study, C. Cross sectional study, D. Ecological study', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Framingham Hea study: Is a classical example of Coho study. Initiated in 1948 by US public health service at Framingham, a town in Massachusetts, USA. Aim: To study the relationship of risk factors (serum cholesterol, blood pressure, weight, smoking) to the subsequent development of Cardiovascular diseases. Sample size of 4469 individuals between age of 30-62 years is taken. Checks incidence of CHD every 2 years.', 'role': 'assistant'}]