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: Dental
[{'content': 'Which of the following laser works on UV waves \nSelect and explain. \nA. CO2 laser, B. Diode, C. Er YAG, D. KrF', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]