Final answer:
According to the law of complementary base pairing, adenine (A) pairs with thymine (T) in DNA, which is consistent with the double helix model by Watson and Crick where purines pair with pyrimidines.
Step-by-step explanation:
According to the law of complementary base pairing in DNA, the correct pairing is that adenine (A) pairs with thymine (T). This rule is a fundamental aspect of the DNA double helix structure as proposed by Watson and Crick. Adenine and thymine form two hydrogen bonds between them, contributing to the stability of the DNA structure. The other correct pair according to this law is guanine (G) with cytosine (C), which are bonded by three hydrogen bonds. This pairing ensures that a purine (A and G, with a two-ring structure) always pairs with a pyrimidine (T and C, with a single-ring structure), maintaining the uniform diameter of the DNA helix.