This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thyroid Gland, Subject name: Surgery
[{'content': 'Which of the following is used in the treatment of well differentiated thyroid carcinoma: \nSelect and explain. \nA. I-131, B. Technetium Scan, C. Phosphate, D. MIBG', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) I131Ref: Schwartz 10th edition, Page 1543* I131 is used in the treatment of metastatic well differentiated cancers.* I123, Tc 99m are all used only for diagnostic purposes.', 'role': 'assistant'}]