This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Anatomy
[{'content': 'Most posterior structure seen in root of lung is \nSelect and explain. \nA. Bronchus, B. Superior pulmonary vein, C. Inferior pulmonary vein, D. Pulmonary aery', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most posterior structure in the root of the lung is bronchus <img src=" /> B D CHAURASIA\'S HUMAN ANATOMY UPPER LIMB THORAX-VOLUME1 SIXTH EDITION Page no-237', 'role': 'assistant'}]