What fibrous protein is a key component of skin, hair, and nails, providing resilience?

• A. Elastin
• B. Collagen
• C. Keratin
• D. Fibronectin

Answer: (C)

Keratin is the correct answer because it is a fibrous protein that serves as a fundamental structural building block in the skin, hair, and nails, contributing to their toughness and resilience. Keratin is a key component of the outer layer of the skin (the stratum corneum) where it forms a protective barrier, as well as in hair and nails, where it provides strength and integrity. This protein is crucial for the overall functionality and durability of these tissues, helping to protect underlying structures from damage, pathogens, and dehydration.

The other options represent different proteins with distinct roles in the body. Elastin, for instance, is vital for providing elasticity to the skin, allowing it to stretch and return to its original shape. Collagen is primarily responsible for maintaining skin structure and firmness, contributing to the skin's tensile strength and structural framework. Fibronectin is involved in cell adhesion and matrix organization but is not a major structural component of skin, hair, or nails like keratin is. Thus, keratin's specific contribution to the strength and protection of skin, hair, and nails makes it the key component in this context.