The correct response to highlight a key difference between gene regulation in prokaryotes and eukaryotes is:
Prokaryotes do not store their genes in a nucleus like eukaryotes do.
This statement reflects that prokaryotes (such as bacteria) have their genetic material located in the cytoplasm, while eukaryotes (such as plants and animals) have their DNA enclosed within a nuclear membrane.
The other statements are either incorrect or misleading regarding the processes of transcription and mRNA processing.