Question

The _________ allow oxygen and carbon dioxide to be exchanged between the lungs. These structures resemble a bunch of grapes.

Answer 1

Alveoli
Alveoli are the little sacs at the end of the bronchioles (Figure below). They look like little bunches of grapes. Oxygen is exchanged for carbon dioxide in the alveoli. That means oxygen enters the blood, and carbon dioxide moves out of the blood.

Answer 2

I do believe the answer is A, alveoli.