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: Surgery
Principle of pole dilatation is: 
Select and explain. 
A. Dilatation of alveolus., B. Expansion of bony socket., C. Both of the above., D. None.
C: Both of the above.
Answer: C: Both of the above. 
Explanation: None