Detailed Explanation:
Correct Answer:

1. beta-1,4-glycosidic linkage

What is Cellulose?
Cellulose is a complex carbohydrate and one of the most abundant organic compounds on Earth. It serves as the primary structural component of plant cell walls, providing rigidity and strength to plants. Cellulose is a linear polymer, meaning it consists of long chains of repeating units (monomers), which in this case are glucose molecules.

Cellulose Structure and Glycosidic Linkage:
The individual glucose units in cellulose are connected by beta-1,4-glycosidic linkages, which means the glucose molecules are bonded at the 1st carbon of one glucose molecule and the 4th carbon of the next glucose molecule in a specific orientation. This beta configuration creates long, straight chains that align and form hydrogen bonds, resulting in the formation of strong fibers.

The beta-1,4-glycosidic linkage provides cellulose with its unique properties, making it highly resistant to hydrolysis by most enzymes. This feature is a reason why cellulose is a major structural component in plant cell walls, as it resists degradation by many microorganisms, unlike starch or glycogen.

Why the Other Options Are Incorrect:

• Option 2 (alpha-1,4-glycosidic linkage):
  Starch, another carbohydrate polymer, contains alpha-1,4-glycosidic linkages. These linkages allow starch molecules to be branched or unbranched, but they differ from the straight, unbranched chains found in cellulose.

• Option 3 (beta-1,3-glycosidic linkage):
  Beta-1,3-glycosidic linkages are found in some other polysaccharides like callose, but they are not part of cellulose.

• Option 4 (alpha-1,3-glycosidic linkage):
  Alpha-1,3-glycosidic linkages are rarely found in polysaccharides and are not a characteristic of cellulose.

Conclusion:
Cellulose is a vital structural polysaccharide composed of glucose molecules linked by beta-1,4-glycosidic linkages. This linkage contributes to the strength and stability of cellulose fibers, which are integral to the structure of plant cell wall.