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': 'The surface marking of the arch of aorta is as follows - \nSelect and explain. \nA. Behind the manubrium sterni, B. 2nd intercostal space, C. 3rd intercostal space, D. Left 2nd costal cartilage', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Arch of Aorta surface marking\n\nRight end of sternal angle\nCentre of manubrium sterni\nSternal end of left second costal cartilage\n\nThese points when connected lies behind the lower half of manubrium sterni.', 'role': 'assistant'}]