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': 'Intrinsic discolouration of teeth which have not originated from developmental defects of the enamel and dentin: \nSelect and explain. \nA. Amelogenesis imperfecta., B. Dentinogenesis imperfecta., C. Erythroblastosis fetalis., D. None.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Intrinsic discolorations such as those occurring\xa0with amelogenesis imperfecta or dentinogenesis\nImperfecta are impossible to eliminate because\xa0they originate from developmental defects of the\xa0enamel and dentin. Hematological disorders such\xa0as erythroblastosis fetalis, thalassemia, and sickle\xa0cell anemia might also be caused due to intrinsic discoloration.', 'role': 'assistant'}]