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 most important reason for retaining healthy roots and prescribing an over denture rather than extractions and a conventional complete denture is: \nSelect and explain. \nA. To preserve the alveolar bone, B. An over denture is easier to construct rather than a complete denture, C. The apparent ease with which the patient adapts to an over denture, D. To retain some degree of proprioception from the healthy periodontal Ligament of the roots', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]