Which One of the Following Statements About the Structure of Proteins

Which one of the following statements about the structure of proteins is incorrect?

A) Disulfide bonds provide strong intrachain interactions.
B) Hydrogen bonding stabilizes the $\alpha$ -helix proteins.
C) Nonpolar groups tend to face the outside of a protein in an aqueous solution.
D) Ionized amino acid side chains can form salt bridges within a protein.
E) Heat can disrupt tertiary structure.