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': 'Route of administration of nitrous oxide is: \nSelect and explain. \nA. Inhalation., B. Oral., C. Intramuscular., D. Intravenous.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]