Question

before endosymbiosis could occur, what must have been present? a. an atmosphere with high levels of oxygen b. aggregated continental crust via plate tectonics c. oceans with salinities close to the modern level d. multiple species of prokaryotic organisms e. an ozone layer, to protect genetic material from the effects of ultraviolet radiation

Answer 1

D. Multiple species of prokaryotic organisms.

Step-by-step explanation:

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