Answer :
From this, you hypothesize that this lineage of dinoflagellates was the result of ENDOSYMBIOSIS. It benefits both organisms.
What is endosymbiosis?
Endosymbiosis is an ecological relationship where one organism is incorporated inside another and it benefits both.
The theory of endosymbiosis states the eukaryotic cells emerged via this type of relationship.
According to the theory of endosymbiosis, prokaryotic organisms that were introduced into primitive eukaryotic cells led to the formation of chloroplasts and mitochondria.
Learn more about endosymbiosis here:
https://brainly.com/question/1698852