What Technique Was Used in the Discovery of the Existence

Multiple Choice

What technique was used in the discovery of the existence in eukaryotic cells of replicons,a discovery in which single DNA molecules were shown to be replicated simultaneously at several sites along their length?

A) scanning electron microscopy
B) confocal laser scanning microscopy
C) autoradiography
D) polyacrylamide gel electrophoresis
E) isoelectric focusing