7.8939 in significant figures

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

Which locations on the map are low-pressure areas? a b c d e

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.