<prompt> R-RNA is mainly produced in -NucleusNucleolusRibosomeEndoplasmic reticulum  <response>: B i.e., NucleolusThe sigma a subunit factor enables RNA polymerase to recognize promoter regions on DNAQ.Like DNA polymerase, RNA polymerase uses nucleoside triphosphate as substrates releases pyrophosphate each time a nucleoside monophosphate is added to growing chain. And as with replcation, transcription is always in 5 -s 3direction. However, incontrast to DNA polymerase, RNA polymerase both in eukaryotes and prokaryotes does not require primer and has no known proofreading activityQ. 