The correct option is C Nirenberg and Matthaei
A set of three nucleotides present on mRNA that encodes information for a particular amino acid is called codon. There are 64 triplet codons coding for 20 amino acids.
Nirenberg and Matthaei cracked the first codon of the genetic code and showed that RNA controlled the production of specific types of protein.
In 1961, they performed an experiment that found the first of the 64 triplet codons. They used nucleic acid homopolymers and cell-free systems for protein synthesis for this experiment.