Skin, hair, and nails consist primarily of this type of nutrient?

Skin, hair, and nails are primarily composed of proteins, making this answer accurate. The most abundant protein in these structures is keratin, which is a fibrous protein that provides strength, resilience, and structural integrity. Keratin is essential not only for the protective barrier functions of skin but also contributes to the hardness and durability of nails and the texture of hair.

In addition to keratin, other proteins play significant roles in the overall health and function of skin, hair, and nails. Collagen, for example, is vital for skin's elasticity and strength. Therefore, the focus on protein as the primary nutrient is well-supported by the biological makeup of these tissues, highlighting the importance of adequate protein intake for maintaining healthy skin, hair, and nails.