Final answer:
The shape of the alveoli and the surrounding capillary beds creates a large surface area, facilitating a high rate of gas exchange between the lungs and the blood. This expansive area allows for efficient diffusion of oxygen into the blood and carbon dioxide out of it. Therefore, the correct option is C
Step-by-step explanation:
The shape of the alveoli and the capillary beds surrounding them is highly significant for efficient gas exchange in the lungs. The correct answer to why the shape is important is (c) it creates a large surface area for pulmonary diffusion. The alveoli are tiny sac-like structures, each surrounded by a network of capillaries, which are essential components of the circulatory system. This anatomical arrangement allows for a large surface area (approximately 75 m² in the human lungs), comparable to the size of a tennis court, due to the presence of roughly 300 million alveoli in each lung.
This expansive surface area, coupled with the thin nature of the alveolar walls, allows for the rapid diffusion of gases. Oxygen enters the blood by passing across these thin membranes from areas of higher concentration to areas of lower concentration, while carbon dioxide, produced as a waste product by cells, diffuses from the blood into the alveoli to be exhaled. This passive process, facilitated by the alveoli's structure, is crucial for providing oxygen to the body and removing carbon dioxide efficiently.