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': 'A space maintainer is least indicated for premature loss of a: \nSelect and explain. \nA. Primary maxillary first molar, B. Primary mandibular first molar, C. Primary mandibular central incisor, D. Primary maxillary central incisor', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]