One example is the country of Iceland which is a large island right on the mid-Atlantic ridge which is where the Atlantic oceanic plate is rifted in two and where the underlying magma wells up to the surface as the two sides to the plate move opposite to each other. The resulting volcanic rock then builds itself up into an island.
For giving you understanding ; we need Free O2 but Oxygen is also available in H20 right why dont we use it !!
As the early atmosphere was reducing as there was no free oxygen but it was later produced by chemoautotrophic bacteria !! Living thing release O2 in atmosphere thus making it oxidising in nature and then life evolves !!
I wanna say A. Desert
Hope this helps!!
where its free (unbound) concentration is lower
