Endosymbiosis is an evolutionary theory that explains the origin of eukarvotes and suggests a specific order in which this might have occurred. Ancestral cells enguited and then began to use the metabolic processes of the smaller cells. Based on shared core processes and features, which statement most accurately describes the order, the theorY and the evolutionary implications for all organisms within domain Eukarya? 1. All ancestral eukaryotes would have most likely consumed a nucleus-ike prokaryote that eventually became the eukaryotic nucleus. These new eukaryotic cells would have had an advantage over prokaryotic cells by acquiring a nuclear conmand center for regulating ocellular activities 2. As Earth was becoming more aerobic, mitochondria would have provided an advantage to host cells by converting toxic axygen into energy for heterotrophic cells. Since mitochondria are found in all eukaryotes, these combinations likely evolved first. Photosnthetic eukaryotes probably acquired an autotrophic prokaryote, which developed an advantageous symbiotic relationship with the host cell 3. As carbon dioxide levels were increasing over time, natural selection would have favored organisms that acquired a photosynthetic prokarvote to convert carbon dioxide into sugars. These would have likely been the first eukaryotic cells. At which point, these ancestral cells engulfed mitochondna-ike prokaryotes that would have provided an even greater advantage for cells in this environment. 4. Ancestral heterotrophic eukaryotes most likely engulted both a heterotrophic and an autotrophic prokaryote, whereas ancestral photosynthetic eukaryotes probably provided the host cell for the first matochondria Over time, natural selection favored these relationships and these cells became ancestors of all eukarvotes

The endosymbiosis theory proposed that a protoeukaryote engulfed the autotrophic bacteria which evolved into the chloroplast and a chemotroph which evolved into the mitochondria.

These events could have taken when the autotrophic bacteria started using carbon dioxide and produced oxygen in the atmosphere that is around 541 million years ago.

When the concentration of the oxygen increased then the mitochondria would have used this toxic gas to produce energy and the chloroplast also formed a symbiotic relationship at that time.

Thus, Option-2 is correct.