Correct Option: A

Ribonuclease P (RNase P) is the endoribonuclease that generates the mature 5′-ends of tRNA by removal of the 5′-leader elements of precursor-tRNAs. Although it carries out a biochemically simple reaction, RNase P is a complex ribonucleoprotein particle composed of a single large RNA and at least one protein component. RNase H (Ribonuclease H) is an endoribonuclease that specifically hydrolyzes the phosphodiester bonds of RNA which is hybridized to DNA. The snRNAs, along with their associated proteins, form ribonucleoprotein complexes (snRNPs), which bind to specific sequences on the pre-mRNA substrate. This intricate process results in two sequential transesterification reactions. These reactions will produce a free lariat intron and ligate two exons to form a mature mRNA. This results in the splicing. CstF is recruited by cleavage and polyadenylation specificity factor (CPSF) and assembles into a protein complex on the 3’ end to promote the synthesis of a functional polyadenine tail, which results in a mature mRNA molecule ready to be exported from the cell nucleus to the cytosol for translation.