This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Radiation treatment planning, Subject name: Radiology
[{'content': 'The radioisotope used for ablation of thyroid gland is \nSelect and explain. \nA. Iodine 123, B. Iodine 125, C. Iodine 131, D. Technetium 99 pertechnate', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) Iodine 131Sutton 7th/1504', 'role': 'assistant'}]