Consider the Following Description of an Area of Current Research

Consider the following description of an area of current research. "Beta-polypeptides are polymers of beta amino acids with backbones one carbon longer than alpha-polypetptides. Like the alpha-polypeptides found in nature, beta-polypeptides can form stable helices and pleated sheets." Which levels of protein structure are cited in this statement?

A) primary
B) secondary
C) tertiary
D) quaternary
E) primary and secondary
F) primary, secondary, and tertiary
G) primary, secondary, tertiary, and quaternary