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: Pathology
What is most commonly involved in carcinoma colon - 
Select and explain. 
A. Caecum, B. Rectosigtmoid colon, C. Transverse colon, D. Ascending colon
B: Rectosigtmoid colon
Answer: B: Rectosigtmoid colon 
Explanation: Ans. is b' i.e., None > Rectosigmoid colonColon cancer o Viually 98% of all concers in the large intesting are adenocarcinoms.o Peak age of presentation is 60-80 years.Overall, adenocarcinoma are distributed approximately equally over the entire length of colon Robbins 8th/e p 824 Note: according to 7th/e of Robbins answer was recotosigmoid. Information given in 7th/e of Robbins were: o The most common site is rectosigmoido The distribution is as follows:?Rectosigmoid colon --> 55% Transverse colon --> 11%Cecum /ascending colon --> 22% Discending colon --> 6%other sites