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': 'Fluorides mostly deposited on the enamel surface at: \nSelect and explain. \nA. Outer surface, B. At DEJ, C. Inner surface, D. Inter prismatic substance', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]