Option A is amino acids and D is peptide bond.
How protein is formed?
Proteins are the polymer of amino acids which means that large number of amino acid combines to form protein molecule. The function of protein is to make muscle cells inside the body. The bonds present in protein are peptide bonds.
Proteins made up the structure of many enzymes or in other words, Enzymes are proteins that are comprised of amino acids which are linked together in one or more polypeptide chains.
So we can conclude that Proteins are the polymer of amino acids.
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