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': 'All the following are the objectives of access cavity preparation EXCEPT \nSelect and explain. \nA. To remove all caries, B. To completely unroof the pulp chamber, C. To achieve straight line access to apical foramen, D. To have converging axial walls for preservation of tooth structure', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]