A) the number of A-T base pairs is always equal to the number of G-C base pairs in all DNA molecules. B) the adenine content in any DNA molecule is always equal to the thymine content. C) the adenine content in any DNA molecule is always greater than the thymine content. D) the guanine content in any DNA molecule is always less than the cytosine content. E) there is no relationship between the ratio of purine and pyrimidine content in any DNA molecule.