It can be observed and tested
This is disproven by the study of cells due to plants don't grow food they making by using sunlight are and water and nutrients <em><u>from </u></em><em><u /></em><u />the soil so it cannot produce the soil due to this fact.
In this question in which is the major source then of free oxygen in the earth's Proterozoic atmosphere is being produce by the evaporation of the ocean water. Hope this answer would be of big help to this assignment then.
