The -helix and -pleated sheet structures of proteins are primarily stabilized by :

Step-by-step solution

The -helix and -pleated sheet are secondary structures of proteins. These structures arise due to the regular folding of the backbone of the polypeptide chain, which is maintained by hydrogen bonding between the >C=O and -NH- groups of the peptide bonds. Peptide bonds are responsible for the primary structure, while disulfide linkages are primarily involved in stabilizing tertiary and quaternary structures. Glycosidic linkages are found in carbohydrates, not proteins. Answer: Hydrogen bonds