According to Chargaff's rule, in the DNA molecule, certain nucleotides always pair with each other in a specific way. This rule states that:
1. Adenine (A) always pairs with Thymine (T)
2. Cytosine (C) always pairs with Guanine (G)
This pairing is due to the specific structures and hydrogen bonding patterns of these nucleotides. Adenine and thymine form two hydrogen bonds, making them complementary to each other, whereas cytosine and guanine form three hydrogen bonds.
By examining the pairings in the answer choices, we can summarize this as:
- [tex]\( A = T \)[/tex] implies that adenine pairs with thymine.
- [tex]\( C = G \)[/tex] implies that cytosine pairs with guanine.
So, the correct option according to Chargaff's rule is:
[tex]\[ \boxed{A = T ; C = G} \][/tex]
