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 of the following radioisotopes are used as systemic radionucleide, except – \nSelect and explain. \nA. Phosphorus-32, B. Strontium- 89, C. Iridium-192, D. Samarium-153', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Radionuclides used for systemic radiotherapy are 32P, 131I, Strontium - 89, Samarium - 153, Yttrium, and Rhenium.', 'role': 'assistant'}]