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
[{'content': 'Rubber band extraction is indicated in haemophiliac patient, as it facilitates the extraction by: \nSelect and explain. \nA. Traction force on PDL, B. Necrosis of alveolar bone, C. Necrosis of PDL, D. Pulling of the PDL', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]