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
Tooth mobility is NOT reversible when there is 
Select and explain. 
A. Inflammation in periodontium, B. Trauma from occlusion, C. Loss of alveolar bone, D. Faulty tooth brushing technique
C: Loss of alveolar bone
Answer: C: Loss of alveolar bone 
Explanation: None