Which one of the following is not a protein ?

Options

A. Wool
B. Nail
C. Hair
D. cellulose

Answer

To solve the question "Which one of the following is not a protein?", we need to analyze the given options and identify which one does not belong to the protein category.

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are:
- A) Wool
- B) Nail
- C) Hair
- D) Cellulose

2. **Understand What Proteins Are**: Proteins are large biomolecules made up of amino acids and are essential for various biological functions. Common examples of proteins include keratin (found in hair and nails) and collagen (found in wool).

3. **Analyze Each Option**:
- **Wool**: Wool is primarily made of keratin, which is a type of protein. Therefore, wool is a protein.
- **Nail**: Nails are also composed of keratin, making them a protein as well.
- **Hair**: Like nails and wool, hair is also made up of keratin, classifying it as a protein.
- **Cellulose**: Cellulose is a polysaccharide (a type of carbohydrate) that is found in the cell walls of plants. It is not a protein.

4. **Conclusion**: Since wool, nails, and hair are all proteins, the only option that is not a protein is cellulose.

Thus, the correct answer is **D) Cellulose**.