The alveoli have certain adaptation for efficient exchange of gases. Which of these is an adaptation?

Alveoli are the numerous small air sacs attached to the bronchiole in the lungs and in close contact with blood vessels for gas exchange essential for the human respiratory system for the diffusion of oxygen and carbon dioxide.

Adaptations of the alveoli:

- Alveoli are folded in a shape that helps in increase their surface area to volume ratio that allows diffusion easily.

- Alveolar walls and blood-carrying vessels are one cell thick helps in providing gases exchange with a short diffusion distance.

- The lining of the alveoli walls are moist that helps in dissolving gases.

- The walls of alveoli are permeable walls - allow gases to pass through.

- closer to blood supply especially capillaries to allow easy movement or diffusion of gases to and from the blood cells.

i believe the answer is c. "baking" is the gerund, while "baking blueberry muffins" would be the gerund phrase. hope this ! : )

the answer would be c