it would be pollen grains travel into the fruit to fertilize the embryo
Explanation:
reproduction in a flower plants begins with the pollination the transfer of pollen from another to stigma on the same flower or the same stigma of ather flower on the same plant self on ather on the one plant to the stigma of another plant cross pollination
Firstly, it cannot be bacteria because bacteria is prokaryotic with no membrane bound organelles. And it's cell wall is made of murein (peptidoglycan).
It certainly isn't a virus virus because a virus has no true cellular structure.
Let's see why we ruled out the other 3 eukaryotic kingdoms:
It can't be an animal because animal cells don't have cell walls and are multicellular.
It can't be fungi because its cell wall is made of chitin, not cellulose.
It can't be a plant because plants are all multicellular.