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
According to WHO classification of periradicutar diseases, code number category K04.4 is 
Select and explain. 
A. Acute apical periodontitis, B. Chronic apical periodontitis, C. Periapical abscess with sinus, D. Periapical abscess with sinus to maxillary antrum
A: Acute apical periodontitis
Answer: A: Acute apical periodontitis 
Explanation: None