Mitochondria evolved before chloroplasts based on which observation?

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All eukaryotes have mitochondria, but not all eukaryotes have chloroplasts. This suggests that mitochondria evolved before chloroplasts in eukaryotic evolution, as they are more universally present in eukaryotic organisms. Choice A is incorrect because mitochondria did not produce the oxygen in the atmosphere - that was the result of photosynthetic bacteria and later chloroplast-containing organisms. Choice B is incorrect because some eukaryotic organisms do not have mitochondria (e.g. some anaerobic protists), and prokaryotes do not have mitochondria either. Choice D is incorrect for the same reason, and choice E is incorrect because the size of organelles is not a reliable indicator of their evolutionary history.

Mitochondria Evolved Before Chloroplasts Based on Which Observation