The correct answer is adenine.
A nitrogen-containing base or nitrogenous base refers to an organic molecule with a nitrogen atom, which possesses the chemical features of a base. The prime biological role of a nitrogenous base is to combine with the nucleic acids together.
Adenine is a nucleobase and its derivatives exhibit numerous functions in biochemistry including cellular respiration, in the form of both the cofactors NAD and FAD and the energy-rich adenosine triphosphate.