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': 'Which of the following permanent teeth is most difficult to distinguish from mesial and distal aspects: \nSelect and explain. \nA. Mandibular central incisor., B. Mandibular lateral incisor., C. Maxillary central incisor., D. Maxillary lateral incisor.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mandibular central incisor is bilaterally symmetrical when viewed labially and incisally.', 'role': 'assistant'}]