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 WHO classification of periradicutar diseases, code number category K04.4 is \nSelect and explain. \nA. Acute apical periodontitis, B. Chronic apical periodontitis, C. Periapical abscess with sinus, D. Periapical abscess with sinus to maxillary antrum', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]