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 has the maximum faciolingual diameter of the crown: \nSelect and explain. \nA. Deciduous maxillary 2nd molar, B. Deciduous maxillary 1st molar, C. Deciduous mandibular 2nd molar, D. Deciduous mandibular 1st molar', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]