A.	active genes in euchromatin, and inactive genes in heterochromatin
B.	amplification of some genes such as rRNA genes
C.	use of different RNA polymerases to transcribe different classes of RNA
D.	spliceosomes that stimulate synthesis of intron-containing hnRNAs Spliceosomes are RNA-protein complexes active in processing of nuclear RNA transcripts in eukaryotic cells. Spliceosomes are not believed to act in regulation of RNA synthesis in the nucleus.
E.	enhancers that can stimulate specific promoters