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': 'Artifical radioisotopsa) Radiumb) Uraniumc) Plutoniumd) Iridiume) Cobalt \nSelect and explain. \nA. ab, B. bc, C. de, D. bd', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Important artificial radionuclides :- Tritium - 1, Carbon - 14, Cobalt - 60, Strontium 89, Strontium - 90, Iodine 131, Cesium 134, Cesium 137, Plutonium - 239, Iridium, Tc - 99.', 'role': 'assistant'}]