Plz and thank you, The diagram below shows the layers of a rock having an ammonite: Which statement about the rock fossils is true?

a. Fossil Y is older than fossil X.
b. Fossil Z is younger than fossil Y.
c. fossil Z existed over many periods of time.
d. Fossil Y existed during the same period as the ammonite.

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 are composed of a different molecular structure compared with eukaryotic poly-a tails. b. prokaryotic poly-a tails have the same functions as eukaryotic poly-a tails, because this process is highly conserved throughout different species. c. prokaryotic poly-a tails aren't important, because prokaryotes don't have nuclei. d. prokaryotic poly-a tails have other functions,because prokaryotes don't have nuclei.