Why Does DNA Denature When the PH Is Raised Above

Multiple Choice

Why does DNA denature when the pH is raised above 9?

A) Protons dissociate from guanine bases disrupting the hydrogen bonding to the other strand.
B) Protons bind to guanine residues giving them additional positive charges which disrupt the hydrogen bonding to the other strand.
C) Protons bind to functional groups that serve as hydrogen-bond acceptors, thus disrupting the hydrogen bonding to the other strand.
D) Protons dissociate from the phosphate groups in the backbone, which disrupts the hydrogen-bonding pattern between strands.
E) None of the answers is correct.