What does Chargaff's rule state about the base composition of DNA?

• A. The amount of purines equals the amount of pyrimidines.
• B. The amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.
• C. The amount of adenine equals the amount of cytosine, and the amount of guanine equals the amount of thymine.
• D. The amount of adenine equals the amount of guanine, and the amount of thymine equals the amount of cytosine.

Answer: (B)