Has done what if it’s a question make it clear for us to answer
<u>Answer:
</u>
The build-up of three oxygen created our ozone layer around two billion years ago.
<u>Explanation:
</u>
- 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.
These 4 Adriatic Sea, Aegean Sea, Black Sea, Ionian Sea
The answer would have to be A.
