The correct answer is (A.) bacteriophages using DNA to infect bacteria.
Explanation
1. In 1952, Alfred Hershey and Martha Chase did experiment to find the genetic material in organisms.
2.Bacteriophages (viruses that affect bacteria) were the key element for Hershey and Chase experiment.
3.In which they concluded DNA as genetic material as bacteriophages use DNA to infect bacteria and not protein.
