Respuesta :
The correct answer is option A
Cause iron in ocean water and terrestrial rocks to rust (oxidize)
Some 2.8 billion years ago, the only evidence of life was in the form of stromatolites and presence of some organic compound with high range of complexity. These complex compounds were prominent in the shale’s of that time. According to Olson, it is established that during those times phosysnthesis just started and the atmosphere of earth by that time was reductive and not oxidative due to which the rocks containing granules of Pyrites (a form of iron) and other minerals could be easily oxidized.
As per the facts it is believed that the presence of oxygen (which was corrosive in nature) made these minerals in the rock to react with oxygen and produce oxidized and decomposed simpler form of these sedimentary rocks which later could be broken up into the sediment granules. The huge deposit of ferric oxide, which is insoluble in ocean water, represents the scenario where iron after getting oxidized became insoluble otherwise it would have got dissolved in the water. But since iron in its oxidative form is insoluble it precipitates out in the sea bed as iron rich sediment on the sea floor.
Along with oxidizing the iron ore , the oxygen released as of photosynthesis proved to be a setback for the anaerobic organism . With later advents it was visualized that the pyruvate when combined with oxygen produced carbon dioxide and water. From here the aerobic form of respiration started and due to this transformation from anaerobic to aerobic respiration the amount of energy produced increased by ten times. Later on oxygen impacted the microbes and they evolved by producing a cell nucleus which could now cover up their exposed DNA. Along with nucleus, cytoplasm was also formed.
