The correct answer is Adenine.
Adenine is termed as nucleobase. It is among the four nucleobases which are found in nucleic acid of DNA. Example of the three nucleobases include, thymine, cytosine, and guanine.
Adenine works in cellular respiration. The other main components oa ATP include, sugar, phosphate , and base.
Sugar is the ribose which is at the center of ATP, base is the adenine which is attached at one side of ribose sugar while phosphate is attached at the other side.