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': 'WHO surveillance is done for all, except- \nSelect and explain. \nA. Polio, B. Viral encephalitis, C. Malaria, D. Relapsing fever', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Viral encephalitis", 'role': 'assistant'}]