Opening of the DNA helix during transcription is facilitated by the RNA Polymerase enzyme, which is a multi-unit enzyme evolved in transcription to synthesize the RNA molecule from the template strand of the DNA molecule.
DNA polymerase – the main function is to duplicate the DNA content of a cell.
DNA ligase – It is a DNA joining and repairing enzyme.
DNA helicase – Separate the two strands of DNA double helix.
So the correct option is (A).