Will give brainlist fast which of the following is a characteristic of scientific investigation? it is based on opinion. it is replicable. it is subjective. it is biased.

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