In a eukaryotic cell, how is transcription regulated? a. transcription factors bind to the tata box to move rna polymerase to the required spot. b. the lac operon blocks transcription when it acts as a repressor and this stops the rate of transcription. c. only one gene is needed so it's turned on or off at one time so proteins to turn on required genes. d. srna interferes with mrna, which prevents the binding of rna polymerase to the substrate agent.