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': 'EDTA was introduced to endodontics by \nSelect and explain. \nA. Nygaard Otsby, B. Ferdinand Munz, C. Ostbey Ingle, D. Rich chalter', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]