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 main function of the horizontal fibres of P.D ligament is \nSelect and explain. \nA. Prevent extrusion, B. Prevent rotation, C. Maintains the mesiodistal width, D. All of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]