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': 'Occlusal offset in an anterior partial veneer crown may generally be necessary to provide: \nSelect and explain. \nA. Retention, B. Conservation of tooth structure, C. Esthetics, D. Structural durability', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]