Which type of protein is found in nails?

Collagen is a protein that primarily provides structural support in connective tissues, such as skin, tendons, and ligaments. While collagen contributes to skin elasticity and overall structural integrity, it is not the main protein found in nails, which instead rely on keratin for their composition.

Disulfide refers to a type of bond that forms between cysteine amino acids in proteins, creating a strong linkage that helps stabilize the protein structure. While disulfide bonds do play a role in the overall structure of keratin, it is not a type of protein itself, but rather a feature found within certain proteins, including keratin.

Fibrous proteins are a broader category that includes several types of proteins characterized by their elongated and thread-like structures, which provide structural support. While keratin is a fibrous protein, labeling it simply as "fibrous" does not specifically identify the protein found in nails, which is distinctly keratin.