Answer:
It discusses Pollution levels in the Air
Explanation: Air can be hazardous to those lungs that are weak. They have something called an Air Quality Alert to warn those with weak lungs to take precautions. Hope this helped!
I believe the correct answer is B. Detrital
<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.
The answer is the first one The Earth rotates on its axis over 24hrs.