Answer:
Uracil
Step-by-step explanation:
DNA and RNA are both nucleic acids with similar structures, but they have a few key differences.
RNA is primarily single stranded, whereas DNA forms a double-stranded helix.
The sugar backbone in a DNA molecule is deoxyribose, whereas in RNA it is ribose.
The nucleotides that make up DNA molecules are adenine, thymine, cytosine, and guanine, whereas nucleotides that make up RNA are slightly different, adenine, uracil, cytosine, and guanine.
In DNA, adenine pairs with thymine, and guanine pairs with cytosine.
In RNA, adenine pairs with uracil, and guanine pairs with cytosine.