Which type of bond is present in the primary structure of a protein?

Only covalent

The answer is (b) only covalent.

The primary structure of a protein is the sequence of amino acids in the protein. The amino acids are linked together by peptide bonds, which are covalent bonds. There are no hydrogen bonds, van der Waals forces, or other types of bonds in the primary structure of a protein.

Here are some additional details about the primary structure of proteins:

• The primary structure of a protein is determined by the DNA sequence of the gene that encodes the protein.
• The primary structure of a protein is relatively stable, and it is not easily changed.
• The primary structure of a protein determines the secondary and tertiary structures of the protein.