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': 'Cyclic trend is shown by ? \nSelect and explain. \nA. Polio epidemic, B. Rabies, C. Influenza pandemic, D. Malaria', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Influenza pandemic", 'role': 'assistant'}]