I'm at a loss between A & C but I'm not sure, I'd go with A
Answer: (1) photosynthesis occurred
Explanation: The photosynthesis process in cianobacteria changed the composition of earth's atmosphera, rising oxygen levels. This could be possible since photosynthesis used energy from the sun to produce energetic intermediaries to synthesize sugars, and as byproduct due to water photolisis, is oxygen.
Answer:
Nucleus stores most of a cell’s DNA...
Explanation:
because it is the control house of the cell..also...