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': 'Feature of aging periodontium is \nSelect and explain. \nA. Lacunae in bone and cementum, B. Increased cell size, C. Increased cell number, D. Scalloping of cementum & alveolar bone surface', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]