Which part of the nail is relatively porous and allows water to pass through?

The nail plate is the correct answer as it is the hard, clear portion of the nail that lies over the nail bed. It is made up of layers of a protein called keratin, which can be somewhat porous, allowing moisture and chemicals to pass through. This characteristic is crucial in maintaining nail health, as it can help prevent excessive moisture loss or absorption that could lead to nail disorders.

In contrast, the nail bed is the skin beneath the nail plate that supports it but is not itself porous in the same way as the plate. The eponychium, or cuticle, acts as a protective barrier for the nail matrix beneath it, preventing pathogens from entering but does not have the same porous nature. The matrix is the tissue that produces new nail cells and is essential for nail growth; it is not involved in the permeability of the nail structure. Thus, the nail plate's composition makes it uniquely suited to allow limited water passage while protecting underlying tissues.