This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
[{'content': 'A 4-year-old boy fell on outstretched hand. X- ray is shown below. Which blood vessel is most commonly affected? \nSelect and explain. \nA. Ulnar artery, B. Radial artery, C. Brachial artery, D. Cubital vein', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C Brachial arteryRef: Essential Orthopedics, Maheshwari 5th ed. pg. 97The image shows displaced supracondylar fracture of humerus and the spike of proximal segment can easily traumatize the brachial artery.', 'role': 'assistant'}]