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
Which of the following Is not an etiological agent for gingival recession 
Select and explain. 
A. Gingival abrasion, B. Gingival ablation, C. Gingival inflammation, D. TFO
D: TFO
Answer: D: TFO 
Explanation: None