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 the following are true about Chronic Obstructive lung disease 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: Answer is D (Decreased diffusing capacity) : Diffusion capacity is not affected in Obstructive lung diseases 9(acute or chronic). It is decreased in restrictive lung disease. Decreased in expiratory flow rate is a hallmark of obstructive lung disease. (i,MEFR) Residual volume is increased & FEVI/FVC is decreased (FEV1 is also decreased). FEV1=forced expiratory volume in one second; FVC=Forced Vital Capacity; FEF25_75=Forced Expiratory Flow at 25%=75% vital capacity; TLC= Total Lung Capacity; DLCO=Diffusion Capacity of the Lung for Carbon monoxide.