Since the Parental Double Helix Must Rotate 360° to Unwind

Multiple Choice

Since the parental double helix must rotate 360° to unwind each gyre of the helix,during the semi-conservative replication of the bacterial chromosome,some kind of "swivel" must exist.What do geneticists now know that the required swivel is?

A) Topoisomerase
B) Helicase
C) A transient single-strand break produced by the action of topoisomerases
D) A transient single-strand break produced by the action of helicases
E) A transient single-strand break produced by the action of Ligase