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
In a 27 yr old male most common cause of a colo-vesical fistula would be: 
Select and explain. 
A. Crohns disease, B. Ulcerative colitis, C. TB, D. Cancer colon
A: Crohns disease
Answer: A: Crohns disease 
Explanation: Diveicular disease is the most common cause of colovesical fistula, followed by colon cancer and Crohn disease. Diveicular disease and colon cancer are rare in people younger than 40 years. Here this patient is young; hence the most suitable answer is Crohn's disease. Ref: ACP Medicine: Volume 1, 2007, Page 816.