Which type of modifications are specifically present in eukaryotes but not in prokaryotes after transcription?

The correct choice is indeed focused on post-transcriptional modifications, which are particularly characteristic of eukaryotic cells and absent in prokaryotic cells.

In eukaryotes, after the transcription of a gene into precursor mRNA (pre-mRNA), several crucial modifications occur before the mRNA is translated into a protein. These modifications include adding a 5' cap, which protects the mRNA from degradation and aids in the initiation of translation, as well as the addition of a poly-A tail at the 3' end, which also helps stabilize the mRNA and facilitates its export from the nucleus. Additionally, eukaryotic pre-mRNA undergoes splicing, a process where introns (non-coding regions) are removed and exons (coding regions) are joined together to produce a mature mRNA transcript. These steps are vital for producing functional mRNA that can be efficiently translated into proteins.

In contrast, prokaryotes do not perform such extensive post-transcriptional modifications. Their mRNA is generally transcribed as a single, continuous sequence and can be immediately translated into protein while it is still being synthesized. This fundamental difference illustrates the complexity of gene expression regulation in eukaryotic organisms compared to