Sister chromatids first appear during the S phase of the cell cycle.
I think this view is NOT compatible with either of these hypothesis illustrated above. This is because each hypothesis presents prokaryotes as two separate groups. Prokaryotes are unicellular organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane bound organelle unlike the eukaryotes which has the membrane bound nucleus and other organelles.
My opinion is that EVEN IF there is anything that humans can do to save our species,
we will argue, debate, play politics, bask in absurd conspiracy theories, fritter around,
dilly dally, and totally ignore the urgency before us, until a time when nothing we're able
to do can any longer have any effect. And that's my opinion.
But anyway, the solution to our problem, the answer to our question is that the stages of stellar evolution, in the correct order, are: a nebula followed by a protostar followed by a main sequence star followed by a red giant and then finally, a white dwarf.
