Which of the following statements about DNA, RNA, and phosphoric acid are not correct?
◦ Phosphoric acid has three dissociable OH groups that can react with alcohols to form phosphoesters.
◦ The two substituted pyrimidines in DNA are cytosine and thymine.
◦ Across the DNA helix, purine bases hydrogen bond only to other purine bases.
◦ both B and C
◦ none of the above