Erwin Chargaff's work on the composition of nucleic acids began in 1944. His findings, which later became known as Chargaff's rules, detail the specific pairings that occur in double-stranded DNA molecules. According to one of Chargaff's rules, a section of DNA molecule that contains 50 base pairs and has 15 adenine bases must also contain -

A. 15 guanine bases

B. 15 cytosine bases

C. 15 thymine bases

D. 15 uracil bases