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: Surgery
Not a predisposing factor for Ca esophagus: 
Select and explain. 
A. Diverticula, B. Human papilloma virus, C. Mediastinal fibrosis, D. Caustic ingestion
C: Mediastinal fibrosis
Answer: C: Mediastinal fibrosis 
Explanation: None