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': 'Emergency or reemergence seen in which of the following organisms -a)  Polio virusb)  Measles virusc)  Nipah virusd)  West Nile viruse)  Hepatitis B virus \nSelect and explain. \nA. abd, B. cde, C. bde, D. ade', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]