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': 'Pandemic are caused by -a)  Hepatitis Bb)  Influenza-Ac)  Influenza-Bd)  Influenza-Ce) Cholera \nSelect and explain. \nA. bd, B. be, C. bcd, D. da', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]