Step 1: Understand 1,4-glycosidic bonds.
These bonds link glucose units in polysaccharides like cellulose.
Step 2: Examine each fibre.
Polynosic, Lyocell, and Ramie are cellulose-based — they contain 1,4-glycosidic bonds.
Silk is a protein-based fibre (fibroin), and does not contain glycosidic linkages.
Step 3: Conclusion.
Only silk is not carbohydrate-based.