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': 'Dentin formed through out the life is \nSelect and explain. \nA. Sclerotic dentin, B. Secondary dentin, C. Reparative dentin, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]