These are grape-like clusters surrounded by <u>blood capillaries</u>
Explanation:
The alveoli (grape-like structures) are surrounded by a network of blood capillaries. They supply blood for decarbonization and oxygenation. The large network provides a large surface area for this gaseous exchange. In addition, the alveoli are moist to help increase the rate of diffusion of the gases in and out of the blood capillaries.
