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': 'The period of communicability of Tetanus is \nSelect and explain. \nA. 7 days, B. None, C. 21 days, D. 14 days', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]