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: Surgery
[{'content': 'Commonest part of subclavian artery to be affected by stenosis is: \nSelect and explain. \nA. First part, B. Second part, C. Third part, D. Equally affected', 'role': 'user'}, {'content': 'Answer: A \nExplanation: MC site of subclavian artery stenosis is the first part of the subclavian artery.\n• MC cause of subclavian artery stenosis: Atherosclerotic disease\n• Left\xa0subclavian artery stenosis is significantly more common than right\n• MC site of stenosis: First part\xa0of the subclavian artery\n• Stenosis typically occurs just distal to the origin of the subclavian artery and lies proximal to the origin of the vertebral artery.\n• Stenosis of the first part of the subclavian artery may give rise to the subclavian steal syndrome\n• Subclavian steal syndrome is characterized by reversed flow in the vertebral artery to compensate for a proximal stenosis in the ipsilateral subclavian artery there by stealing blood from the ‘brain’ to feed the ‘arm’.', 'role': 'assistant'}]