Answer the following question given this paragraph: 

In the chest, the trachea divides as it enters the lungs to form the right and left bronchi (bronchus, singular). These passages are covered with mucus and tiny hairs called cilia. The mucus traps any remaining particles in the air. The cilia move and sweep the particles and mucus toward the throat so they can be expelled from the body.


Q: In the chest, what divides as it enters the lungs to form the right and left bronchi?


A:
trachea