The correct option is this: THE DISCOVERY OF CODONS.
Codons refers to a sequence of three DNA or RNA nucleotides which corresponds to a particular amino acid or a stop signal during protein synthesis. Thus, the genetic codon is used to translate the information that are encoded within genetic materials into proteins. The genetic codons was discovered by Marshall Nirenberg and Heinrich Matthaeis, who deciphered the entire genetic codes by matching amino acids to synthetic triplet nucleotides.