The right answer is Marshall Nirenberg and Heinrich Matthaei.
In the so-called "triplet binding test" by Nirenberg and Matthaei short messenger RNA (mRNA) pieces with known base sequences were synthesized. These mixed the two researchers with ribosomes that had been isolated from bacteria. Investigations initially showed that ribosomes and mRNA attached to each other. Then Nirenberg and Matthaei fulfilled all the conditions necessary for protein biosynthesis and put the necessary ingredients in a test tube: purified ribosomes, a mixture of all 20 amino acids (from experiment to experiment, another amino acid was radioactively labeled) and finally a synthetic mRNA, with a known base sequence. After all of the components were assembled and allowed to react, the mixture was loaded on a filter that retained ribosomes, mRNA, and newly synthesized protein, but allowed free amino acids to pass through (filtrate). Then it was examined whether radioactive material was in the filtrate or was just retained.