- A Collagen
- B Elastin
- C Keratin
- D Actin
Correct answer: C. Keratin
Explanation: Keratin is a fibrous structural protein found in hair, nails, and skin. It is rich in the amino acid cysteine which forms disulfide bonds.
Concept context
Carbohydrates, proteins, lipids, nucleic acids, and enzyme kinetics. Essential foundation for understanding metabolism.