Which of the following is due to chronic smoking:

Ans. (a) Centri-acinar emphysemaRef: Harrison 18th edition, Chapter 13* Centri-acinar lesions are more common and severe in the upper lobes, particularly in the apical segments.* In severe centriacinar emphysema the distal acinus also becomes involved, and so, as noted, the differentiation from panacinar emphysema becomes difficult.* This type of emphysema is most commonly seen as a consequence of cigarette smoking in people who do not have congenital deficiency of a^antitrypsin.