The answers D
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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:
oxygenated blood is pumped to the body by the left ventricle.
