• Peptidoglycan (Murein) Structure: The bacterial cell wall peptidoglycan backbone consists of alternating linear units of:
• $N$-acetylglucosamine (NAG)
• $N$-acetylmuramic acid (NAM)
• Glycosidic Linkage: NAG and NAM are linked together by $\beta(1\to 4)$ glycosidic bonds.
• Enzymatic Cleavage: Lysozyme specifically hydrolyzes these $\beta(1\to 4)$ glycosidic bonds between NAM and NAG, lysing bacterial cell walls.

Correct option: (3) B1- 4 linkages

• Dextran Linkages: Dextran is a complex, branched glucan polymer synthesized from sucrose by lactic acid bacteria (e.g., Leuconostoc mesenteroides):
• Major Linkages: The linear polysaccharide backbone consists predominantly of $\alpha(1\to 6)$ glycosidic linkages ($\gt 95\%$ of bonds).
• Branch Points: Minor branches are attached via $\alpha(1\to 3)$, $\alpha(1\to 2)$, or $\alpha(1\to 4)$ linkages.
• Clinical Application: Used as a plasma volume expander and in Sephadex gel filtration chromatography matrices.

Correct option: (2) a1-6 linkages

• Glycosaminoglycans (GAGs): Long, unbranched heteropolysaccharides consisting of repeating disaccharide units composed of an amino sugar and an uronic acid:
• Hyaluronic Acid: A classic non-sulfated GAG consisting of alternating units of D-glucuronic acid and $N$-acetylglucosamine linked by $\beta(1\to 3)$ and $\beta(1\to 4)$ bonds. It is found in synovial fluid, vitreous humor, and connective tissues.
• Other Choices: Cellulose is a structural plant glucan, peptidoglycan is a bacterial cell wall polymer, and inulin is a plant storage fructosan.

Correct option: (1) Hyaluronic acid

• Classification of Polysaccharides:
• Structural Polysaccharides:
• Chitin: Homopolysaccharide of $N$-acetyl-$\beta$-D-glucosamine with $\beta(1\to 4)$ linkages; provides rigidity to arthropod exoskeletons and fungal cell walls.
• Peptidoglycan: Structural polymer of alternating NAG and NAM cross-linked by peptide bridges, forming the rigid outer envelope of bacterial cells.
• Storage Polysaccharides:
• Starch and (B) Glycogen: Energy storage polymers composed of D-glucose linked by $\alpha(1\to 4)$ and $\alpha(1\to 6)$ glycosidic bonds.
• Conclusion: Therefore, (C) and (D) only are structural polysaccharides.

Correct option: (4) (C) and (D) only.