Excertion is best described as the removal of what

What did not occur in the proterozoic eon a)the oxygen levels increase greatly in the atmosphere,b)the emergence of the eukarya , c)muti cella’s eukaryotic organisms began to diversify,d)anaerobic bacteria kept thriving with more oxygen

There are fewer than 100 naturally occurring elements in the universe, but there are millions of different unified substances. explain how this can be true.

Which condition causes storms to occur