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': 'Thermafil is \nSelect and explain. \nA. An endodontic obturater, B. An enlarging instrument, C. An instrument to remove pulp, D. Is a cold gutta percha technique', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]