Regarding Protein Structure, Which, If Any, of the Following Statements

Multiple Choice

Regarding protein structure, which, if any, of the following statements is incorrect?

A) The primary structure is the linear sequence of amino acids.
B) The secondary structure is the path followed by the polypeptide backbone over its length.
C) The secondary structure of every protein contains an alpha-helix.
D) The structure of an alpha-helix is primarily determined by hydrogen bonding between chemical groups on the side chains.