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: Surgery
[{'content': 'Half life of iodine 131 is? \nSelect and explain. \nA. 6 days, B. 4 hours, C. 8 days, D. 13.5 hours', 'role': 'user'}, {'content': 'Answer: C \nExplanation: lodine 131 is used for radioiodine ablation.', 'role': 'assistant'}]