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
Gingivitis appears on the radiograph as 
Select and explain. 
A. Loss of alveolar bone, B. Pocket formation, C. Change in bone trabeculations, D. No observed changes
D: No observed changes
Answer: D: No observed changes 
Explanation: None