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 among the following is produced by a linear accelerator? \nSelect and explain. \nA. X rays, B. Beta rays, C. Gamma rays, D. Neutrons', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Linear accelerator is source of powerful x-rays. The name linear accelerator comes from the fact that electrons are produced in the machine and accelerated in a straight line. They then smash into a metal target within the machine and, because the energies involved are so high, produce high energy x-rays. Cyclotron is used to produce Gamma rays.', 'role': 'assistant'}]