Which two bases are purines in DNA?

In DNA, purines are a class of nitrogenous bases that consist of a two-ring structure, which distinguishes them from pyrimidines, which have a single-ring structure. The purines found in DNA are adenine and guanine.

Adenine plays a crucial role in the formation of the nucleotide building blocks of DNA, pairing with thymine during DNA replication and transcription. Guanine also participates in base pairing, specifically with cytosine.

Understanding the structure and function of these bases is fundamental in genetics and molecular biology since they dictate the genetic code through complementary base pairing. The other options contain either pyrimidines or incorrect combinations of purines, which do not reflect the composition of DNA.