In the primary structure of a protein, amino acids are joined together by bonds.

In the primary structure of a protein, amino acids are joined together by peptide bonds otherwise called CO-NH bonds. Amino acids unite together and will form a peptide bond further it forms a polypeptide chain by combined with many peptides.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products

c. is the correct answer