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 main objective of obturation is: \nSelect and explain. \nA. Fill the canal and prevent apical percolation of fluids, B. Fill the canal and prevent discolouration of teeth, C. Fill the canal to give support to restoration, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]