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': 'Small pox vaccine was invented by: \nSelect and explain. \nA. Lious pauster, B. Jenner, C. John Snow, D. Eugene', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Jenner', 'role': 'assistant'}]