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 anesthetic agent is frequently\nused for conscious sedation? \nSelect and explain. \nA. Nitrous oxide and oxygen, B. Chloral hydrate, C. Diazepam, D. Ether', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]