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: Pathology
[{'content': 'Clinical evidence of dentinogenesis imperfecta is \nSelect and explain. \nA. Defective enamel and dentine, B. Defective dentine and obliterated pulp chamber, C. Increased rate of caries, D. Oligodontia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]