<u>Answer:
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The build-up of three oxygen created our ozone layer around two billion years ago.
<u>Explanation:
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- The ozone layer is a part of the stratosphere which is located right after the troposphere in the atmosphere of the Earth.
- The ozone gas is made up of the abundance of three oxygen molecules combining with the ultraviolet radiation emitted by the Sun.
- The development of the ozone layer happened around two billion years ago when the oxygen concentration levels on the planet began to rise slowly and gradually.
Answer:the weather in Mount Everest is harsh winds, sub freezing temperatures, and thin air. And what this means for hikers is that because of this it causes unpredictable weather conditions as in avalanches and ice storms. Which puts the hikers in danger
Explanation: I just read the article and thought about it. Hope this helps
D. single- and simple multi-celled organisms
Although more complex animals like invertebrates and multi-celled organisms began to appear, it was very late compared to the original, simpler organisms for which the Precambrian time is characterized by.
Hi, I think it’s true .( just trying to help ) :)) good luckkk
