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: Radiology
[{'content': 'Earliest feature of pulmonary venous hypeension \nSelect and explain. \nA. Kerley B lines, B. Upper lobar diversion of vessels, C. Left atrial enlargement, D. Pleural effusion', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e., Upper lobar diversion of vessels Upper lobe venous diversion is the first radiological sign of pulmonary venous hypeensonQ.', 'role': 'assistant'}]