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': 'Three doses of tetanus vaccine provides immunity for \nSelect and explain. \nA. 10 years, B. 1 year, C. 5 years, D. 15 years', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]