Answer:
Option b, Phosphodiester bond
Explanation:
Proteins are sequence of amino acids. Two amino acids are joined by peptide bond. Therefore, proteins are also known as sequence of polypeptide chains. These polypeptides chains have four level of structures:
Primary structure
secondary structure
Tertiary structure
Quaternary structure
Primary structure is simply a sequence of amino acids. In secondary, tertiary and Quaternary structure, various interactions are present.
Disulfide bond, hydrogen bond and salt bridge stabilizes tertiary structure of the protein.
Phosphodiester bond is present as link between two nucleotides and thus, present in the backbone of nucleic acid (RNA and DNA)
Therefore, the correct option is option b
