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
What is the most commonly involved in carcinoma colon - 
Select and explain. 
A. Caecum, B. Rectosigmoid colon, C. Transverse colon, D. Ascending colon
B: Rectosigmoid colon
Answer: B: Rectosigmoid colon 
Explanation: None