Chargaff' a rule states that in an organism:

Options

A. amount of adenine `(A)` is equal to that of thymine `(T)` and amount of guanine `(G)` is equal to that of cytosine `(C )`
B. amount of adenine `(A)` is equal to that of guanine `(G)` and the amount of thymine `(T)` is equal to that of cytosine
C. amount of adenine `(A)` is equal to that of cytosine `(C )` and the amount of thymine `(T)` is equal to that of guanine `(G)`
D. amount of all bases are equal

Answer

A

Explanation

`E`. Chargaff observed certain regularities that can be seen in the percentage of heterocyclic bases obtained from the `DNA` of a variety of species. Chargaff pointed out that for all species examined:
(1) The mole percentage of adenine is nearly equal to that of thymine (i.e., `% A % T ~= 1`) and the mole percentage of guanine is nearly eaual to that of cytosine (i.e., `% G% C ~= 1`)
The total mole percentage of purines approximately equal to that of the pyrimidines, that is `(%G + %A)//(%G C% ~= 1)`. Chargaff also noted that the ratio which varies form species to species is the ratio `(%A + %T)//(%G + %C)`. He also noted that whereas this ratio is characteristic of the `DNA` of a given species, it is the same for `DNA` obtained from different tissues of the same animal, and does not vary appreciably with the age or conditions of growth of individual with the age or conditions of growth of individual organisms within the same species.