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 advantages of overdenture are all of the following, except \nSelect and explain. \nA. Preservation of alveolar bone, B. Aesthetics, C. Retention, D. Support', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]