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': 'Collagen fibers are absent in: \nSelect and explain. \nA. Acellular extrinsic fibre cementum, B. Acellular afibrillar cementum, C. Mixed stratified cementum, D. Intermediate cementum', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]