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': 'The function of a root canal sealer is: \nSelect and explain. \nA. To fill the gap between the tooth and the filling, B. As an antiseptic, C. Aids in healing, D. Provide strength', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]