Gas exchange in the lungs is facilitated by:

Consider the role of the capillary network: Alveoli are surrounded by an extensive network of capillaries. This close proximity ensures a large surface area for gas exchange and maintains a steep concentration gradient for oxygen and carbon dioxide.

Eliminate incorrect options: Thick cartilage in the bronchioles does not facilitate gas exchange, as bronchioles are primarily involved in air conduction. Similarly, nitrogen has low solubility in blood plasma and does not play a significant role in gas exchange. Active transport is not involved in oxygen movement across the alveolar membrane; instead, diffusion is the primary mechanism.