Which of the following is not one of Chargoff's rules?

a. The amount of A, T, G, and C in DNA varies from species to species, but not within species

b. In each species, the amount of A = T and the amount of G = C

c. In every species, the amount of purines (A+G) equals the amount of pyrimidines (T+C)

d. In every species, DNA is a simple repeating polymer made up of the same four nucleotides.

The answer is:

d. In every species, DNA is a simple repeating polymer made up of the same four nucleotides.

Explanation:

Chargaff's rules are based in the quantitative relationship of the nucleotides (adenine, guanine, cytosine and thymine) that form part of the double strand of DNA.

One of the rules states that the amount of adenine (A) is the same as thymine (T), and that the amount of guanine (G) is the same as cytosine (C). A=T, G=C

Being said in another way: the total amount of purine bases it's the same as the total amount of pyrimidine bases. (A + G = C + T).

The second rule states that the composition of DNA (the amount of nucleotides) is different from one species to other, but nor within species.