Nails, horns and hooves contains

Options

A. chitin carbohydrate
B. keratin
C. both
D. none

Answer

**Step-by-Step Solution:**

1. **Identify the Structures**: The question asks about nails, horns, and hooves. These are all hard structures found in mammals.

2. **Understand Their Function**: Nails, horns, and hooves serve as protective coverings and play a role in locomotion and defense. They are part of the mammalian exoskeleton.

3. **Determine the Composition**: The primary component of nails, horns, and hooves is a type of protein. Specifically, these structures are made up of keratin, which is a fibrous protein.

4. **Differentiate from Other Options**:
- **Chitin**: This is a carbohydrate that forms the exoskeleton of arthropods and is also found in the cell walls of fungi. It is not found in nails, horns, or hooves.
- **Carbohydrates**: While they are essential biomolecules, they do not constitute the primary structural material of nails, horns, and hooves.
- **Keratin**: This is the correct option as it is the structural protein that makes up these hard structures.
- **Both/None**: Since keratin is the only correct answer, the options "both" and "none" are incorrect.

5. **Conclusion**: Therefore, the correct answer to the question is that nails, horns, and hooves contain keratin.

**Final Answer**: Nails, horns, and hooves contain keratin.

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