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: Medicine
[{'content': 'Increased Alveolar arterial difference in PaO2 is seen in all except? \nSelect and explain. \nA. COPD, B. Pulmonary Edema, C. GBS, D. Interstitial Lung Disease', 'role': 'user'}, {'content': 'Answer: C \nExplanation: GBS is extra-parenchymal restrictive lung disease, so P(A - a)O2 is normal.', 'role': 'assistant'}]