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': 'Primary function of cementum is \nSelect and explain. \nA. Root formation, B. Attachment, C. Repair, D. Protection', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The primary function of cementum is to provide attachment of the tooth to alveolar bone socket through Sharpey’s fibres.', 'role': 'assistant'}]