The correct answer is: Cellulose.
Cellulose is a structural polysaccharide found in the cell walls of plants. It is the most abundant organic compound on Earth, and it is the main component of wood, paper, and cotton. Animals do not have cellulose in their cells because they do not have cell walls.
Proteins are essential for all living things. They are made up of amino acids, and they are used to build and repair tissues, make enzymes, and transport molecules. Animals and plants both have proteins.
Fats are a type of lipid that is used for energy storage and insulation. Animals and plants both have fats.
Starch is a type of carbohydrate that is used for energy storage. Plants store starch in their seeds, fruits, and roots. Animals do not store starch, but they can digest it.
In conclusion, the correct answer is cellulose. Cellulose is a structural polysaccharide found in the cell walls of plants. It is the most abundant organic compound on Earth, and it is the main component of wood, paper, and cotton. Animals do not have cellulose in their cells because they do not have cell walls.