Answer:
I believe that the answer is c.
Explanation:
car·ti·lage
/ˈkärdlij/
noun
firm, whitish, flexible connective tissue found in various forms in the larynx and respiratory tract, in structures such as the external ear, and in the articulating surfaces of joints. It is more widespread in the infant skeleton, being replaced by bone during growth.
This process is called Melting.
I'm guessing its so they can be able to diagnose a patient and see whether they need treatment or not