The correct option is B RNA polymerase
Transcription is when RNA is made from DNA. During transcription, RNA polymerase makes a copy of a gene from the DNA to mRNA as needed. During transcription, the DNA site at which RNA polymerase binds is called as promoter. Transcription commences with one or more sigma factor protein binds to the RNA polymerase holoenzyme, allowing it to bind to promoter DNA. RNA polymerase creates a transcription bubble, which separates the two strands of the DNA helix. This is done by breaking the hydrogen bonds between complementary DNA nucleotides.