Answer:
The correct answer would be radioactive phosphorus in viral DNA was shown to enter bacterial cells.
Hershey and Chase used the radioactive sulfur (³⁵S) and radioactive phosphorus (³²P) to mark protein and DNA in bacteriophage.
They then allowed this bacteriophage to infect the bacteria and then checked that which radioactive material was passed into the infected bacteria.
Infected bacteria showed the presence of radioactive phosphorus in their DNA.
Thus, they concluded that the genetic material was DNA not protein.