Which of these is a type of polysaccharide?

Cellulose is a type of polysaccharide, which is a carbohydrate consisting of long chains of monosaccharide units. It is a structural component of the cell walls in plants and plays a crucial role in providing rigidity and support. Polysaccharides like cellulose are characterized by their large, complex structures and are generally not soluble in water, making them different from simpler carbohydrates.

In contrast, fructose and glucose are monosaccharides, which are the simplest form of carbohydrates and consist of single sugar units. Lactose, while being a disaccharide made up of two monosaccharides (glucose and galactose), does not fit the definition of a polysaccharide, which must contain three or more monosaccharide units linked together. Therefore, cellulose stands out as the correct answer due to its classification and functions in living organisms.