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
The most common cause of acquired aeriovenous fistula is? 
Select and explain. 
A. Bacterial infection, B. Fungal infection, C. Blunt trauma, D. Penetrating trauma
D: Penetrating trauma
Answer: D: Penetrating trauma 
Explanation: Ans. is 'd' i.e. Penetrating trauma "Penetrating injuries are the most common cause, but fistulas are sometimes seen after blunt trauma" - CSDT