Question

the alveoli are the ____.
tiny air sacs that allow us to breathe in oxygen and exhale carbon dioxide
parts of the respiratory system where the air first enters our body
parts of the respiratory system that is responsible for transporting inhaled air to the lungs

Explanation:

To solve this, we analyze each option:

• Option 1: Alveoli are tiny air sacs in the lungs where gas exchange (oxygen in, carbon dioxide out) occurs. This matches their function.
• Option 2: The air first enters the body through the nose/mouth, not alveoli. Eliminate.
• Option 3: Structures like the trachea and bronchi transport air to the lungs, not alveoli. Eliminate.

Answer:

A. tiny air sacs that allow us to breathe in oxygen and exhale carbon dioxide