Answer :
Final answer:
Endosymbiosis enabled the formation of early protists by incorporating photosynthetic prokaryotes into eukaryotic cells.
Explanation:
Endosymbiosis is the process that most likely enabled the formation of early protists. During primary endosymbiosis, a photosynthetic prokaryote was engulfed by a heterotrophic eukaryote, leading to the formation of organelles like chloroplasts. This process eventually allowed for the evolution of more complex eukaryotic cells.
Learn more about Evolution of early protists through endosymbiosis here:
https://brainly.com/question/45223677