The bronchi divide into smaller tubes known as the _______________.Question 19Answera.bronchib.bronchiolesc.trachead.alveoli

The bronchi divide into smaller tubes known as the bronchioles.

Here's a step-by-step explanation:

1. The respiratory system is responsible for taking in oxygen and expelling carbon dioxide. The process of breathing starts when we inhale air through our nose or mouth.

2. The air then travels down the trachea, or windpipe.

3. The trachea divides into two tubes called bronchi (one bronchus for each lung).

4. Each bronchus then divides into smaller tubes called bronchioles.

5. The bronchioles further divide and eventually lead to tiny air sacs called alveoli, where the exchange of oxygen and carbon dioxide takes place.

So, the correct answer is b. bronchioles.