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
[{'content': 'Blood supply of sigmoid colon is by: \nSelect and explain. \nA. Middle colic aery, B. Marginal aery, C. Left colic aery, D. All', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B. i.e. Marginal aery', 'role': 'assistant'}]