Which part of the nail, if destroyed, will not grow back?

The correct choice is the matrix, which is the part of the nail responsible for producing new nail cells. If the matrix is destroyed, the nail cannot regenerate because there is no longer a source of new growth. The matrix is located beneath the base of the nail, and it provides the foundation from which the nail plate emerges.

When the matrix is compromised, the growth cycle of the nail is interrupted, leading to permanent loss of the nail in that specific area. This is distinct from other parts of the nail; for instance, the nail plate can be damaged or removed but will typically grow back if the matrix remains intact. Similarly, the cuticle acts as a protective barrier and can re-establish itself after being removed or damaged, and the nail bed, which supports the nail plate, does not affect the growth when compromised. Therefore, understanding the structure and function of the matrix is crucial for grasping why its destruction results in the permanent loss of nail growth.