Answer:
b. Disulfide bond
Explanation:
Covalent linkage or bonding is a type of bond in which electrons are shared between atoms in a compound or molecule. Each atom contributes to the shared electron.
This is the case of disulfide bonding i.e. S-S, in which two thiol groups (-SH) share electrons with one another. The process of oxidation between two cysteine (amino acid) molecules forms this bond. Hence, Disulfide bond is characterized by a covalent linkage.
