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': 'Dilatation of upper lobe veins is a reliable sign of: \nSelect and explain. \nA. Cardiac decompensation, B. Pulmonary ht., C. Emphysema, D. Silicosis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Cardiac decompensation', 'role': 'assistant'}]