Regarding the Sugar Residues in Nucleic Acids, Which, If Any

Multiple Choice

Regarding the sugar residues in nucleic acids, which, if any, of the following statements is incorrect?

A) The sugar is always based on a heterocyclic ring that consists of one oxygen atom and four carbon atoms, one of which is connected to a fifth carbon atom, the 5' carbon atom.
B) The internal sugar residues in a DNA strand normally have free hydroxyl groups, unlike those in an RNA strand.
C) Bases are covalently linked to the carbon 1' atoms of the sugars.
D) Neighboring sugar residues are linked to each other by a phosphodiester bond that connects the 3' carbon atom on one sugar to the 5' carbon atom of its neighbour.