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
Earliest feature of pulmonary venous hypeension 
Select and explain. 
A. Kerley B lines, B. Upper lobar diversion of vessels, C. Left atrial enlargement, D. Pleural effusion
B: Upper lobar diversion of vessels
Answer: B: Upper lobar diversion of vessels 
Explanation: B i.e., Upper lobar diversion of vessels Upper lobe venous diversion is the first radiological sign of pulmonary venous hypeensonQ.