Which event was a major source of atmospheric oxygen? photosynthesis

volcanic eruptions

decomposition of water

outgassing

Photosynthesis was a major source of atmospheric oxygen.

Explanation:

Earth's atmosphere was not the same as it is in the past. For a larger portion of Earth's history, the atmosphere actually didn't have an atmosphere or the one it had was not suitable for complex lifeforms to develop. This all changed because of one major event, the process of photosynthesis.

Initially, it was the cyanobacteria that started to use this process in order to produce their own food and energy. Basically, this process meant that the cyanobacteria, and a lot of later organisms, were taking in carbon dioxide, use it for their own needs, and release the oxygen. The oxygen was released into the ocean and into the atmosphere, which resulted in a gradual change in the composition of the atmosphere to a degree where it was suitable for larger organisms to start to develop.

the answer is:

c. islam and christianity

explanation:

islam and christianity are widely practiced in africa. islam is practiced due to its spread from the middle east into africa, and christianity is practiced due to the colonization of africa by the british empire.

for e2020. the answer would be some directions from the mountain range so we can find mt. whitney. to locate which direction is north, you should use a   compass. this would not only find mt. whitney, but also becuase of this long paragraph you would get points because it's not like anyone actually reads your work becuase once they read the first sentence it sounds dumb enough to not read becuase i'm not good at answering this but the answer is compass for your benefit.

for e2020 ; -;