According to Chargaff's Rule, in a given DNA sample, which pair of bases will exist in equal quantities?

Chargaff's Rule states that in any given DNA sample, the amount of adenine (A) will be equal to the amount of thymine (T), and the amount of guanine (G) will be equal to the amount of cytosine (C). This means that when one base is quantified, its complementary base will be present in an equivalent quantity.

Adenine pairs with thymine through two hydrogen bonds, leading to their equal representation in double-stranded DNA. This pairing is essential for the double-helix structure of DNA and supports accurate DNA replication and transcription processes. Therefore, the correct answer reflects the fundamental pairing rules of nucleotides in the DNA structure.

While the other options present pairs of bases, they do not satisfy the criteria set by Chargaff's Rule. Adenine does not pair with guanine or with cytosine in equal quantities, as they are not complementary pairs. Similarly, guanine and thymine do not pair as complementaries and thus cannot be considered in equal quantities either. Understanding these base pairing rules is crucial for grasping the molecular biology concepts surrounding DNA structure and function.