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': 'All the following radioisotopes are used in painful body metastasis except \nSelect and explain. \nA. Strontium-89, B. Samarium-153, C. Tin-117, D. Yttrium', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Yttrium is used in Medical Synovectomy.', 'role': 'assistant'}]