Study the following diagram and consider the statements following in regard to the labels .
I. A is lined by pseudostratified ciliated columnar epithelium bearing glandular cells and cartilaginous ring.
II. B is the part of lung where major exchange of gases takes place.
III. C decreases both in diameter and thickness as it gets take place.
IV. D is part of lung where exchange of gases do not take place.
Choose the correct set of statements.
A. I , II and III
B. II, III and IV
C. I and III
D. II and IV
