This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Large Intestine, Rectum, and Anal canal, Subject name: Anatomy
Watershed zone of large intestine - 
Select and explain. 
A. Cecum, B. Ascending colon, C. Rectosigmoid, D. Transverse colon
C: Rectosigmoid
Answer: C: Rectosigmoid 
Explanation: Ans. is 'c' i.e.. Rectosigmoid o There are areas of colon with poor blood supply resulting from incomplete anastomosis of marginal arteries. These are watershed areas of colon and include :1. Splenic flexure (Griffith point): Watershed area between superior mesenteric artery and inferior mesenteric artery.2. Rectosigmoid junction (Sudeck's point) : Watershed zone between inferior mesenteric artery and internal iliac artery.