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': 'Cyclical trend of occurrence of disease is shown by all except \nSelect and explain. \nA. Measles, B. Rubella, C. Influenza, D. Polio', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Cyclical trend is occurance of disease in cyclical pattern\nEg :\n\nMeasles : every 2-3 years.\nRubella : every 6-9 years.\nInfluenza : every 10-15 years (pandemic).\n\nPolio cases occurance is considered as epidemic / short term fluctuation.', 'role': 'assistant'}]