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': 'Primary teeth differ from permanent teeth in following aspects \nSelect and explain. \nA. Thickness of enamel and dentin, B. Pulp chambers are longer, C. Roots are flaring, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]