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
All pulmonary function abnormalities are seen in COPD it , Except - 
Select and explain. 
A. Decreased FEV1, B. Decreased maximum expiratory flow rate, C. Increased residual volume, D. Decreased diffusing capacity
D: Decreased diffusing capacity
Answer: D: Decreased diffusing capacity 
Explanation: None