Oxygen first entered earth's atmosphere when one-celled organisms resembling modern cyanobacteria began to carry out the process of

a fossilization
b evolution
c photosynthesis
d erosion

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

Brainliest ! which would require more force to move or slow down between a bowling ball and a soccer ball? explain why?

The earth's oceans are made up of chlorine, and trace elements. a) carbon, oxygen b) oxygen, silicon c) hydrogen, oxygen d) nitrogen, oxygen