The double helix model of DNA explained Chargaff's rules because


A.
adenine could hydrogen-bond with thymine and guanine could hydrogen-bond with cytosine to hold the helix together.


B.
a helix repeats itself many times over, so the four bases in DNA can repeat themselves many times.


C.
adenine and thymine are found in one strand of the double helix and guanine and cytosine are found in the other strand.


D.
adenine could change places with thymine while guanine could change places with cytosine.