Are codons a group of three ribonucleotides or deoxyribonucleotides?

Dear student, Codons are units, made up of triplet bases . Codons are present on mRNA and codes for specific amino acid. So codons are group of three bases not group of ribonucleotides or deoxyribonucleotides. For example:- Suppose, for amino acid -lysine, codon present on mRNA is AAA. Thanks and regards