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: Pathology
All are obstructive lung disease except 
Select and explain. 
A. Emphysema, B. Interstitial fibrosis, C. Asthma, D. Bronchitis
B: Interstitial fibrosis
Answer: B: Interstitial fibrosis 
Explanation: None