Cellulose is a polymer of :

 Cellulose is polymer of $\beta -D-$glucose. 

• Cellulose Structure: Cellulose is a natural polymer made up of long chains of glucose molecules. These glucose units are connected by β(1→4)-glycosidic bonds, forming a straight, unbranched chain.
• Glucose Units: Each glucose molecule in cellulose is a six-carbon sugar, known as D-glucose. The specific linkage between these glucose units gives cellulose its unique properties, such as high tensile strength and insolubility in water.
• Comparison with Other Options:
  • Fructose: Fructose is a different type of sugar (a ketohexose) and is not a building block of cellulose.
  • Ribose: Ribose is a five-carbon sugar (a pentose) and does not contribute to the structure of cellulose.
  • Sucrose: Sucrose is a disaccharide composed of glucose and fructose; it is not a component of cellulose.

Therefore, among the given options, cellulose is a polymer of glucose. Understanding that cellulose is a polymer of glucose is fundamental in fields like biochemistry and materials science, as it explains the structural role of cellulose in plant cell walls and its applications in producing materials like paper and textiles.