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': 'Which of the following is the most cranial structure in the root of the left lung? \nSelect and explain. \nA. Pulmonary artery, B. Bronchus, C. Pulmonary vein, D. Bronchial artery', 'role': 'user'}, {'content': 'Answer: A \nExplanation: pulmonary artery is seen in upper part of left lung root.', 'role': 'assistant'}]