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': 'Epidemiology of cholera in England was classified by- \nSelect and explain. \nA. John Snow, B. Winslow, C. Chadwick, D. Howard huger', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., John snow John snow, an English epidemiologist, studied the epidemiology of cholera and estabilished the role of drinking water in the spread of cholera.", 'role': 'assistant'}]