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 relapse of crowding after orthodontic treatment occurs mainly because of: \nSelect and explain. \nA. Horizontal fibers, B. Oblique fibers, C. Gingival fibers, D. Transseptal fibers', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]