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': '↑ energy linear acceleration used in- \nSelect and explain. \nA. X-ray, B. Cathode rays, C. Photon rays, D. α - rays', 'role': 'user'}, {'content': 'Answer: A \nExplanation: X-ray tubes produce X-ray by accelerating electrons to high energies.', 'role': 'assistant'}]