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': 'A severe blow to a permanent anterior tooth, not causing fracture frequently leads to \nSelect and explain. \nA. Permanent looseness, B. Immediate pulpal death, C. Pulpal death, but only if treatment is delayed too long, D. Pulpal death regardless of treatment', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]