"Ribonucleotides", I think, you aren't giving us answer choices
Uracil is present in RNA and not in DNA
RNA includes cytosine and uracil as pyrimidine bases while DNA has cytosine and thymine. The difference is Uracil as Uracil is not present in DNA. Uracil is less expensive to produce than thymine, and may be used for its use in RNA. But in the case of DNA, uracil is readily produced by chemical degradation of cytosine.
