When damaged, which of the following will cause the hair growth to be inhibited?

The correct answer, which is the papilla, is essential in the hair growth process because it contains blood vessels that supply nutrients and oxygen to the hair follicle. The papilla plays a critical role in regulating hair growth by providing the necessary sustenance for healthy hair development. When the papilla is damaged, it can greatly affect the hair's ability to grow, leading to inhibited hair growth or even hair loss.

The hair follicle houses the entire hair structure and serves as an anchor for the hair, but damage to the follicle itself does not always directly result in inhibited growth if the papilla remains intact. The bulb, found at the base of the follicle, is where hair growth is initiated, but like the follicle, it requires a healthy papilla to support ongoing growth. The dermis, on the other hand, provides structural support and contains various skin components, but it does not directly influence the hair growth cycle in the way the papilla does. The papilla is central to the hair's connection to the supply of vital nutrients, making its integrity crucial for hair growth to continue effectively.