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': 'Conservation of tooth structure during biomechanical preparation of crown can be done by \nSelect and explain. \nA. Use of partial-coverage restorations, B. Minimum practical convergence angle (taper) between axial walls, C. Preparation of the occlusal surface, so reduction follows the anatomic planes, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Tooth structure is conserved by using the following guidelines:\xa0\n\nUse of partial-coverage rather than completecoverage restorations.\nPreparation of teeth with the minimum practical convergence angle (taper) between axial walls.\nPreparation of the occlusal surface so reduction follows the anatomic planes to give uniform thickness in the restoration.\nPreparation of the axial surfaces so tooth structure is removed evenly; if necessary, teeth should be orthodontically repositioned.\nSelection of a conservative margin compatible with the other principles of tooth preparation.\nAvoidance of unnecessary apical extension of the preparation.', 'role': 'assistant'}]