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': 'Osteoblast covering the periodontal surface of the alveolar bone constitute a \nSelect and explain. \nA. Modified periosteum, B. modified endosteum, C. periosteum, D. endosteum', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]