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
The most important reason for retaining healthy roots and prescribing an over denture rather than extractions and a conventional complete denture is: 
Select and explain. 
A. 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
A: To preserve the alveolar bone
Answer: A: To preserve the alveolar bone 
Explanation: None