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': 'In endodontic-periodontal lesion pulpal necrosis \nSelect and explain. \nA. Follows periodontal changes, B. Precedes periodontal changes, C. Impedes periodontal changes, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]