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
Investigation of choice for colon cancer is 
Select and explain. 
A. CECT, B. Barium enema, C. Barium swallow, D. Colonoscopy
D: Colonoscopy
Answer: D: Colonoscopy 
Explanation: Colonoscopy is for Ca. Colon.