Out of the given options, the statement that correctly describes one of Chargaff's rules regarding DNA is the ratio of adenine (A) to thymine (T) is approximately 1:1 in a DNA molecule.
Option 2 is correct
Chargaff's rules highlight specific base pairing patterns in DNA. They state that the amount of adenine (A) always equals the amount of thymine (T) and the amount of guanine (G) always equals the amount of cytosine (C).
Option 3 is incorrect because the G:C ratio is not always 2:1. It can vary depending on the organism and specific DNA sequences.
Option 4 is incorrect because uracil (U) is only found in RNA, not DNA. Thymine (T) replaces uracil in DNA.