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': 'The best space maintainer for the early Loss of upper primary incisor is the pin and tube maintainer, because \nSelect and explain. \nA. It is aesthetically acceptable, B. It does not injure the upper tip, C. It is easy to fabricate, D. It allows Lateral growth of the bone', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]