The correct answer is option 'C', which is cellulose.

Cellulose is a type of polysaccharide, which is a polymer made up of a large number of glucose units. It is one of the most abundant organic compounds on Earth and is an essential component of plant cell walls.

Here is a detailed explanation of why cellulose is the correct answer:

What are polymers?
- Polymers are large molecules made up of repeating subunits called monomers. These monomers can be the same or different and are linked together through chemical bonds to form a long chain.

What is cellulose?
- Cellulose is a polysaccharide, which means it is a polymer made up of many sugar molecules (glucose units) bonded together.
- It is a complex carbohydrate that is found in the cell walls of plants.
- Cellulose is a linear polymer, meaning the glucose units are linked together in a straight chain.

Structure of cellulose:
- Cellulose is made up of beta-glucose units, which are connected by glycosidic bonds.
- The beta-glucose units are oriented in such a way that their hydroxyl (-OH) groups alternate between pointing up and down.
- This alternating arrangement allows the cellulose chains to form strong hydrogen bonds with each other, creating a rigid and stable structure.

Function of cellulose:
- Cellulose provides structural support to plant cells and helps maintain their shape.
- It gives rigidity to plant cell walls, allowing plants to stand upright.
- Cellulose also forms the basis of dietary fiber, which is important for digestive health in humans.

Comparison with other options:
- Protein: Proteins are not polymers of glucose units. They are polymers of amino acids and have different functions in living organisms.
- Fructose: Fructose is a monosaccharide, not a polymer. It is a simple sugar found in fruits and other sweet foods.
- Polyester: Polyesters are polymers, but they are not made up of glucose units. They are formed by the reaction of dicarboxylic acids with diols.

In conclusion, cellulose is the correct term for polymers made up of a large number of glucose units. It is a polysaccharide found in plant cell walls and provides structural support to plants.