Answer:
its a barrier that goes around everything else
Prokaryotic cells reproduce asexually which makes it easier for them to multiply because all they have to do is split in half where as eukaryotic cells reproduce sexually so they have to find another cell to meet with in order to reproduce.
I think the correct answer would be A. The yolk sac becomes the placenta. It is membranous sac that is attached to the embryo. It provides all the nutrition and the blood cells needed by the embryo. It is also called the umbilical vesicle.
