<u>Answer</u>:
Option 1.Eukaryotic cells first seen
Option 5. oxygen builds up in the atmosphere
<u>Explanation</u> :
- The name <em>Proterozoic eon</em> is derived from a Greek word which means earlier life.
- This eon represents the time just before complex life started proliferating on earth.
- One of the most important events that took place during this eon was <em>build up of oxygen in the atmosphere</em>.
The fossil evidence also shows the occurrence of <em>advanced single-celled eukaryotes.</em>
<em>So the events that define the Proterozoic eon are eukaryotic cells first seen and oxygen build up in the atmosphere. </em>
Hello!
<h3>⭐What does polar mean? </h3>
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- D. An unequal sharing of electrons
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<em><u>Chemical polarity or only polar is a property of molecules that represents the separation of electric charges in the same molecule (see also electric dipole). ...</u></em>
I hope I have helped you :D
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atte:
<u>Angela</u>
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22 percent of solar radiation is filtered by clouds and may cause sunburn on cloudy days.
According<span> to the SCF, up to </span>eighty %<span> of the sun's </span>ultraviolet illumination<span> rays </span>will taste<span> clouds. T</span>his is<span> </span>the rationale folks<span> often </span>find yourself<span> with serious sunburns on overcast days if they've </span>hung out<span> outside with no sun protection.</span>
