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
Periodontal ligament is thinnest at 
Select and explain. 
A. Apex, B. Coronal, C. Crestal, D. Fulcrum of axis of rotation
D: Fulcrum of axis of rotation
Answer: D: Fulcrum of axis of rotation 
Explanation: None