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: Radiology
[{'content': 'Half life of I131 is \nSelect and explain. \nA. 4 hours, B. 8 days, C. 4 days, D. 10 days', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. 8 days', 'role': 'assistant'}]