Chargaff’s Rules helped in deducing the double helix structure of DNA. Which statement best summarizes Chargaff’s Rules?

• A. The total number of purines in a DNA molecule is always greater than the total number of pyrimidines.
• B. The proportion of adenine and thymine varies significantly between different species.
• C. The amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.
• D. DNA consists of a repeating sequence of adenine, thymine, cytosine, and guanine.

Answer: (C)