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
In Rubber band extraction, extraction of the tooth occurs because of: 
Select and explain. 
A. Tearing of PDL., B. Necrosis of PDL., C. Both, D. None
B: Necrosis of PDL.
Answer: B: Necrosis of PDL. 
Explanation: Pressure of elastic leads to ischaemia and hence necrosis of PDL.
Due to this, tooth becomes mobile and leads to extraction of tooth.