Which one of the following discoveries involving dna happened first?

A. Hershey and Chase used bacteriophages to confirm that DNA was the genetic material in genes.

According to the central dogma of molecular biology,  the process of protein synthesis in living organisms follows the  order: DNA →RNA→ Protein.Information for synthesis of a particular protein is copied (transcribed) from DNA onto mRNA in a process called transcription, in the cell nucleus.mRNA (messenger RNA) leaves the cell nucleus and enters the cytoplasm where it attaches to a ribosome.  tRNA (transfer RNA)  begins to decode (translate) the information on the attached mRNA in a process called translation and fetches amino acids corresponding to this information from the pool of free amino acids in the cytoplasm, and brings them to the ribosome where they are joined together into a chain and thus the protein is formed.

The basic repeating unit of nucleic acids are known as nucleotides. a nucleotide consists of three distinct chemical groups.