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': 'Ceificate of vaccination of Yellow Fever is valid for how many years: September 2010 \nSelect and explain. \nA. 1 year, B. 2 years, C. 5 years, D. 10 years', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. D: 10 years', 'role': 'assistant'}]