What forms the base pairs in the DNA structure?

In the structure of DNA, the base pairs are formed by specific complementary interactions between nitrogenous bases. Adenine (A) pairs with Thymine (T) using two hydrogen bonds, while Cytosine (C) pairs with Guanine (G) through three hydrogen bonds. This complementary base pairing is essential for the stability and functionality of the DNA double helix.

The correct choice reflects the precise pairings that occur in DNA. The pairing of adenine with thymine and cytosine with guanine ensures that the genetic information can be accurately replicated and transcribed during biological processes. This pairing mechanism is a fundamental aspect of molecular biology and genetics.

Other options either include bases that do not pair in DNA (like uracil, which is found in RNA instead of thymine) or involve incorrect pairings that do not occur in the DNA structure. Thus, the answer accurately encapsulates the specific interactions that underpin DNA's structure and function.