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 Iodine 131 is – \nSelect and explain. \nA. 8 hours, B. 8 days, C. 8 weeks, D. 8 months', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]