This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Concept of health and disease, Subject name: Social & Preventive Medicine
[{'content': 'WHO surveillance is done for all expect \nSelect and explain. \nA. Polio, B. Viral Encephalitis, C. Malaria, D. Relapsing fever', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Diseases under WHO surveillance Polio Rabies Relapsing fever Influenza Salmonella Malaria Louse born typhus', 'role': 'assistant'}]