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': 'Enamel is laid down \nSelect and explain. \nA. Mainly by odontoblasts, B. Mainly by ameloblasts, C. Only on odontoblasts, D. Only by ameloblasts', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]