The Isthmus of Panama Cut Off Gene Flow Between Atlantic

The Isthmus of Panama cut off gene flow between Atlantic and Pacific populations of a species of fish.The cessation of gene flow led to the accumulation of genetic differences between the populations,which led to reproductive isolation.Now Atlantic and Pacific populations of this fish are separate species,and even if they were again to come into contact with each other,they could not interbreed.This situation illustrates the phenomenon of

A) sympatric speciation.
B) Dobzhansky-Muller speciation.
C) allopatric speciation.
D) reinforcement.
E) temporal isolation.