Final answer:
Keratin is a tough fibrous protein that is a major component of the skin, providing strength and protection. It forms the corneum, the outermost layer of the skin.
Step-by-step explanation:
The tough fibrous protein that is a major component of the skin is keratin. Keratin provides strength and protection to the skin, hair, and nails. It forms the outermost layer of the skin called the corneum, which helps prevent moisture loss and acts as a barrier against pathogens and environmental damage.
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