Recall that nucleic acids DNA and RNA are composed of nitrogenous bases paired with sugar and phosphate groups.
Identify the four nitrogenous bases found in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G).
Understand that RNA differs from DNA in one key base: RNA contains uracil (U) instead of thymine (T).
Therefore, the nitrogenous bases in RNA are adenine (A), uracil (U), cytosine (C), and guanine (G).
Confirm that inosine is not a standard base in RNA, and thymine is replaced by uracil in RNA, so the correct set is adenine, uracil, cytosine, and guanine.