A is the best explanation assuming that these regions already have conditions to yield crops, as the global climate warms, and the further away from the centre of the globe you live, it’s logical to assume that the average optimal temperature for crop yielding will move further north.
They use the process of osmosis (a special type of simple diffusion).
Environmental microbiomes
Well known functions of these are to provide nutrients like nitrogen and phosphorus to plants as well as producing growth hormones.
