This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen & Pelvis, Subject name: Anatomy
[{'content': 'Choose the appropriate lettered structure in this CT scan of the abdomen at the level of the upper lumbar vertebra. Which structure is a direct branch of the aorta and supplies blood to the ascending and transverse colons? \nSelect and explain. \nA. A, B. B, C. C, D. D', 'role': 'user'}, {'content': 'Answer: D \nExplanation: (d) The superior mesenteric artery, a direct branch of the aorta, supplies blood to the ascending and transverse colons.', 'role': 'assistant'}]