This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nuclear medicine, Subject name: Radiology
[{'content': 'Which of the following is a Alpha emitter? \nSelect and explain. \nA. Plutonium-236, B. Carbon-11, C. Oxygen-15, D. Samarium -153', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Alpha (a) radiation: Consists of heavy, positively charged paicles, each of which contains two protons and two neutrons. Alpha Emitters : Americium-241 Plutonium-236 Uranium-238 Thorium-232 Radium-226 Radon-222 Polonium-210 84', 'role': 'assistant'}]