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': 'According to Ellis and Davey classification a fracture of 51 involving dentin and associated loss of vitality is classified as \nSelect and explain. \nA. Class 2, B. Class 4, C. Class 8, D. Class 9', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]