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': 'Acellular cementum \nSelect and explain. \nA. Has no cells, B. Has cells trapped in cementum called cementocytes, C. Is formed throughout life, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]