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': 'Who discovered X-rays: September 2007 \nSelect and explain. \nA. Roentgen, B. Curie, C. Becquerel, D. Gray', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A: Roentgen X-rays were produced firstly in 1895 by Roentgen.', 'role': 'assistant'}]