One function of the poly-a tail on eukaryotic mrna sequences is to the mrna be transported from the nucleus to the cytoplasm. prokaryotic mrna also has a poly-a tail. choose the best explanation of the prokaryotic poly-a tail.
a. prokaryotic poly-a tails have the same functions as eukaryotic poly-a tails, because this process is highly conserved throughout different species.
b. prokaryotic poly-a tails are composed of a different molecular structure compared with eukaryotic poly-a tails.
c. prokaryotic poly-a tails have other functions, because prokaryotes don't have nuclei.
d. prokaryotic poly-a tails aren't important, because prokaryotes don't have nuclei.

C. Prokaryotic poly-A tails have other functions, because prokaryotes don't have nuclei.

Explanation:

In eukaryotes, the poly-A tails help in import of mRNA from cytosol to nucleus with the help of proteins named as importins and then export of mRNA from nucleus to cytosol with the help of proteins named as exportins. In prokaryotes they serve the function of mRNA degradation instead. In prokaryotes, mRNA doesn't need to be imported and exported because they do not have a well defined double membranous organelle named as nucleus. All of their genetic material lies in the cytosol in the form of nucleoid.

In eukaryotes,  poly-A tails serve many other functions apart from export and import like it imparts stability to mRNA, facilitates degradation of mRNA and increases translation efficiency by helping in circularization.