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': 'Hardest vital tissue among the following is: \nSelect and explain. \nA. Enamel, B. Dentin, C. Cementum, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Dentin is the hardest vital tissue, while the enamel is the hardest non-vital tissue.', 'role': 'assistant'}]