This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
[{'content': 'Best-know large sample study programme for coronary heart disease is \nSelect and explain. \nA. North kerelia study, B. Framingham study, C. Standford study, D. Oxford study', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]