Multiple Choice
Why did the presence of cyanobacteria on Earth in the past allow humans to exist?
A) It was the first form of life.
B) It oxygenated the atmosphere.
C) It fertilized the soil to let plants grow.
D) It increased the carbon dioxide in the atmosphere, causing the greenhouse effect.
E) It was the first life form based on DNA.
Correct Answer:
Verified
Correct Answer:
Verified
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