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: Anatomy
Blood supply of sigmoid colon is by -a) Middle colic arteryb) Marginal arteryc) Left colic arteryd) Sigmoid artery 
Select and explain. 
A. c, B. d, C. ab, D. bd
D: bd
Answer: D: bd 
Explanation: Blood supply of sigmoid colon comes from the sigmoid artery and marginal artery of sudeck .
The marginal artery is an arterial cascade formed by anastomosis of -ileocolic, rt. colic, middle colic, left colic, and sigmoid arteries. And blood supply of colon (Large intestine) is derived from the marginal artery.