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: Pathology
An acute apical abscess is usually a result of: 
Select and explain. 
A. Periodontal pocket, B. Occlusal interference, C. Necrotic pulp, D. Chronic gingivitis
C: Necrotic pulp
Answer: C: Necrotic pulp 
Explanation: None