Consider the following statements regarding the structure of proteins and choose the correct option.
I) The primary structure of a protein refers to the three-dimensional arrangement of amino acids.
II) In the secondary structure of proteins, amino acid sequences are often organized into right-handed helices or β-pleated sheets.
III) The tertiary structure of proteins involves the arrangement of multiple polypeptide subunits.
IV) The quaternary structure of a protein, as seen in human hemoglobin, consists of multiple polypeptides or subunits arranged in a specific architecture.