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': 'Most efficient removal of hard tissue is done by \nSelect and explain. \nA. Er laser, B. Argon visible laser, C. Nd:YAG, D. HO: YAG', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]