Polysaccharides

The correct answer is:

Option 4: Cellulose

Explanation:

Cotton fibers are primarily made of cellulose, a complex polysaccharide. Cellulose is a structural carbohydrate found in the cell walls of plants and provides rigidity and strength to plant structures like cotton fibers.

The other options are incorrect because:

Glycogen (Option 1) is a storage polysaccharide found in animals, primarily in the liver and muscles.

Starch (Option 2) is a storage polysaccharide found in plants, but it is not the main component of cotton fibers.

Insulin (Option 3) is a protein hormone, not a polysaccharide.

Thus, cellulose is the polysaccharide present in cotton fibers.