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 the WHO classification of Periradicular  diseases periapical abscess with sinus to the oral cavity is coded as: 
Select and explain. 
A. K04.60, B. KO4.61, C. K04.62, D. KO4.63
C: K04.62
Answer: C: K04.62 
Explanation: None