This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Large intestine, Subject name: Surgery
What is the investigation of choice for the diagnosis of colon cancer? 
Select and explain. 
A. Barium enema, B. Colonoscopy + biopsy, C. USG, D. CT scan
B: Colonoscopy + biopsy
Answer: B: Colonoscopy + biopsy 
Explanation: IOC for diagnosis of colon cancer- Colonoscopy + biopsy IOC for staging of colon cancer- CECT Most impoant prognostic factor- stage (TNM) Single independent most impoant prognostic factor- LN status