Which of the following is incorrect with respect to Chargaff's rules ?

• A

  Phosphate and deoxyribose sugar occur in equal amount.

• B

  The ratio of $\frac{\mathrm{A} +\mathrm{G}}{\mathrm{T} +\mathrm{C}}$is specific for a species.

• C

  There are double hydrogen bonds between A and T and triple hydrogen bonds between G and C.

• D

  Molar concentration of purines is equal to the concentration of pyrimidines.