There was a massive earthquake that separated a large population into two groups on opposite sides of a valley. If members of this population remain geographically isolated, what cannot occur?

Sympatric speciation

Explanation:

There may be more than one answer here, but concerning speciation, sympatric speciation can't occur because of the geographic isolation (must be living in the same environment for this to occur).

answer

crater lake was formed when mount mazama produced a large eruption and collapsed to form a caldera, which then filled with water forming a lake.

i think that the best answer would be c.

tell me if im wrong : )