What happens during the initiation step of DNA transcription?

• A. The mRNA detaches from the RNA polymerase as the RNA polymerase leaves the DNA strand.
• B. RNA polymerase attaches to the DNA at the promoter sequence of the gene.
• C. A ribosome attaches to the initiation codon of a completed mRNA strand.
• D. RNA polymerase moves along the template strand of the DNA creating an mRNA strand.