Answer: A( adenine) G (Guanine) C (Cytosine) T (Thymine) U (Uracil)
Why? Nucleic acids are polynucleotides—that is, long chainlike molecules composed of a series of nearly identical building blocks called nucleotides. ... Each nucleic acid contains four of five possible nitrogen-containing bases: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U).