Biogeographic isolation : Isolation through distribution of Species in geographic space and time
so , one of the answer is The isolation of two populations of the same species
By doing this, decrease the chance of any cross breeds between species, which eventually will led to Speciation
Freeze-thaw, onion skin (exfoliation), chemical and biological weathering
Plato answer:
Stimulation of a neuron causes a change in the charge inside the cell from negative to positive. This change is caused by ions, which are atoms with an electrical charge, moving across the cell. This change within the cell is consistent with the definition of an electric charge.
I believe the correct answer is the second option, or b.