Which of the following BEST describes what alveoli are?

A. They are the smallest tubes in the respiratory system.

B. They have a small amount of surface area.

C. They are found on the end of bronchioles.

D. They are compromised of millions of cells.

Respuesta :

A.

It's not C because they are spread in clusters throughout the lung, not D because they are really one thick cell , surface area isn't that small