What most likely occur b/w 3.5 to 2.5 billion yrs that could account for change in atmosphere oxygen? plz help

Question

many scientist believed that the 1rst prokaryotes organism on earth evolve about 3.5 billion yrs ago. About 2.5 billion yrs ago the oxygen concentration of earth atmosphere began to increase significantly.

what most likely occur b/w 3.5 to 2.5 billion yrs that could account for change in atmosphere oxygen?

a. fossilization of early prokaryotes

b evolution of anaerobic organism

c. evolution of photosynthesing organism

d condensation of atmospheric water into ocean

plz answer

thankx

Answer 1

Odd question!  It won't occur because it already happened.  The only option that could've increased the oxygen supply is c.

'Anaerobic organisms' would be completely wrong, so ignore that.  They're organisms that don't require oxygen and, in some cases, even find the stuff poisonous.

Answer 2

C..... the process of photosynthesis produces oxygen.  So there y'go.

Answer 3

b. evolution of anaerobic organism

Answer 4

You question is in the present tense and confusing people. The question should be: what most likely occured between 3.5 and 2.5 billions years ago that could account for the change in atmospheric oxygen?

The answer is C - the evolution of photosynthesizing organisms.

Anaerobic organisms do not consume oxygen, but they don't create it, either. Fossilization is rather irrelevant in the grand scheme of oxygen creation. And condensation of atmospheric water also has nothing to do with oxygen production, although it does provide a bit more habitat for choice c - the photosynthesizing organisms.