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 of the following are true about COPD except: 
Select and explain. 
A. Decreased FEV1, B. Decreased MEFR, C. Increased RV, D. Decreased diffusion capacity
D: Decreased diffusion capacity
Answer: D: Decreased diffusion capacity 
Explanation: None