11. Which of the following statements is true regarding protein structure? a. Tertiary structure refers to the shape of a polypeptide resulting from interactions between the side chains (“R” groups) of various amino acids.b. Secondary structure refers to the sequence of amino acids in a polypeptide.c. Primary structure refers to the coils and folds that result from hydrogen bonds between the carboxyl and amino groups in a polypeptide.d. Quaternary structure refers to the overall protein structure that results from the aggregation of polypeptide subunits.e. Both a and d are correct.