The nitrogenous base that pairs with guanine is cytosine. Cytosine (C) is one of the four main bases found in DNA and RNA, along with adenine (A), guanine (G), and thymine (T) in DNA or uracil (U) in RNA. In the DNA double helix, cytosine forms a base pair with guanine through the establishment of three hydrogen bonds, ensuring the stability of the genetic structure.
