Answer:
d
Step-by-step explanation:
primary structure of a protein is the sequence of amino acids. secondary structure is the curling or folding of the polypeptide chain into Alpha helices or Bita pleated sheets due to formation of H bonds. tertiary structure is the overall 3D shape of the protein determined by the interactions between R groups. Quaternary structure is the specific 3D shape of a protein that is determined by the multiple polypeptide chains or prosthetic groups bonded together.