The oxygen in the upper atmosphere combine to form ozone layer (o3) that allows to colonize surface water.
Explanation:
The fossil stomatolites are formed at about 3.0 ga laminated bacteria. they form the sediments to fall into a thin film of bacteria, these bacteria binds with the sediment and grows through it.
Cynobacteria uses water, CO2 and sunlight to create their own food and produce oxygen as a by product. The significance of stromatolites is that they are earliest fossil evidence life on earth.
They were first organism to photosynthesis and produce oxygen.
I would say A...just because when it comes to flexibility everyone is different.
Hope this helps!!!
My guess is let him freeze his butt off then have his coat waiting at the door when he realizes he was wrong. It's called letting him learn from experience.
I think the answer would be, The Pericardium.
