Among the options listed, alpha helix is an example of a secondary protein structure. Secondary structures in proteins are formed by the folding of the polypeptide chain into distinct shapes, commonly alpha helices and beta sheets.
The other options, such as aspartic acid (asp), phenylalanine (phe), tyrosine (tyr), and glycine (gly), are individual amino acids, while globular proteins, hemoglobin, and fibrous proteins refer to the overall structure and function of proteins rather than their secondary structure. Hemoglobin is a globular protein composed of multiple secondary structures, but it isn’t itself classified as a secondary structure. Thus, the correct answer is the alpha helix.