What are the proteins called that rapidly degrade most mRNA in prokaryotes?

The correct response to the question is that the proteins involved in the rapid degradation of most mRNA in prokaryotes are exonucleases. Exonucleases are enzymes that cleave nucleotides one at a time from the ends of RNA or DNA molecules, essentially degrading the RNA strand from either the 5' or 3' end. In prokaryotes, mRNA is relatively short-lived, and these exonucleases play a crucial role in controlling gene expression by regulating mRNA stability and turnover. This allows cells to quickly respond to changes in their environment by degrading unneeded mRNA, thereby preventing unnecessary protein synthesis.

The other options provided, though related to RNA metabolism and cellular processes, do not specifically function in the context of degrading mRNA in prokaryotes. RISC is a complex involved in RNA interference and does not degrade mRNA directly but rather facilitates the silencing of specific mRNA molecules. Proteases are enzymes that degrade proteins, not RNA. Ribosomes are the cellular machinery responsible for translating mRNA into proteins; they play no direct role in mRNA degradation. Therefore, the role of exonucleases is specifically related to effectively managing mRNA stability in prokaryotic cells.