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': 'Which is provided by linear accelerator- \nSelect and explain. \nA. Electron, B. Neutron, C. Proton, D. Infrared rays', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]