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: Pharmacology
[{'content': 'The dentist who first used Nitrous oxide for the abolition of pain due to dental extraction was \nSelect and explain. \nA. Harper David, B. Harvey william, C. Horace wells, D. Hunter John', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]