Answer:
D. build them up and breaks them down
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Answer:
<em>The correct option is C) C-shaped cartilage rings </em>
Explanation:
The trachea is commonly known as the wind-pipe. The trachea can be described as about a 4 inch long passage from which the air travels into the bronchi and lungs. The pathway of the trachea is kept open by C- shaped cartilages which are lined all over in the trachea. The C-shaped cartilages protects as well as maintain the shape of the wind-pipe. The rigidity of the trachea arises from the C-shaped cartilages.