Question

question 21 what are the tiny air sacs in the lungs called? a bronchi b bronchioles c diaphragm d alveoli

Explanation:

The alveoli are the tiny air - sacs in the lungs where gas exchange occurs. Bronchi are the main airways into the lungs, bronchioles are smaller airways branching from the bronchi, and the diaphragm is a muscle involved in breathing, not an air - sac in the lungs.

Answer:

D. Alveoli