Gene expression might be altered at the level of post-transcriptional processing in eukaryotes rather than pro

Question

...karyotes because of which of the following?

a Eukaryotic exons may be spliced in alternative patterns.

b Prokaryotes use ribosomes of different structure and size.

c Prokaryotic genes are expressed as mRNA, which is more stable in the cell.

d Eukaryotic coded polypeptides often require cleaving of signal sequences before localization.

e Eukaryotic mRNAs get 5' caps and 3' tails.

Answer 1

a,d,& e are all post transcriptional events in eukaryotes.

Answer 2

This is a strangely worded question.  It's asking "why", but the answers are all "how".

I believe the answer the author is looking for is a.  Alternative splicing is a type of post-transcriptional regulation in eukaryotes but not in prokaryotes that can alter gene expression.

c. is not true.  b., d., and e. don't affect gene expression at the post-transcriptional level.