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
Pan acinar emphysema is seen in 
Select and explain. 
A. Smoking, B. Chronic bronchitis, C. α1 - antitrypsin deficiency, D. Spontaneous pneumothorax
C: α1 - antitrypsin deficiency
Answer: C: α1 - antitrypsin deficiency 
Explanation: Centriancinar - Smokers, chronic bronchitis.
Pan acinar - α1 - antitrypsin deficiency.