Please Help Quick ASAP Hurry A species of squirrels were split in half when a tornado swept through the forest.
Half of the squirrels ended up in an environment near a pond. The other half ended up on rocky ground. They were too far apart to reunite. Ten years later, both of the squirrel populations' allele frequencies had changed to be more fit for their environments. The pond squirrel population and the rocky ground squirrel populations could no longer mate together.

What was the cause of this speciation?
A. geographic isolation
B. gene flow
C. a decrease in the mutation rate
D. a change in climate