The Structures of Cytosine and Guanine Are Shown Below $-\mathrm{NH}_{2}$ Group on Guanine Hydrogen Bonds with the
A) -

The structures of cytosine and guanine are shown below. In DNA the $-\mathrm{NH}_{2}$ group on guanine hydrogen bonds with the

A) - $\mathrm{NH}_{2}$ group on cytosine.
B) doubly bonded ring nitrogen on cytosine.
C) -NH- ring nitrogen on cytosine.
D) carbonyl oxygen on cytosine.