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Answer:
d. all of the above
Explanation:
all the above answers are correct about Science
When babies are born, their brains contain about a hundred billion of neurons. However, a few of these brain cells are connected. At age three, there are one thousand trillion connections formed. The brain starts to cut off unused connections at the age of eleven.
The answer is C. Fertilization. hope I helped.
<u>Answer:</u>
Cyanobacteria start producing pure oxygen around 200 million years ago.
<u>Explanation:</u>
Many scientists believed that Earth did not have any oxygen. Cyanobacteria or the blue green algae are the microbes which produced oxygen for the first time with the help of photosynthesis. This was around 4.5 billion years ago: after Hadean eon.
They were very simple, but they produced oxygen in the early earth’s atmosphere. So, they brought evolution on earth. This “blue-green algae” exists in salt water, rocks and soils and play a major role in maintaining the ecosystem.