Two species of antelope ground squirrels are separated by the Grand Canyon. They are hypothesized to have descended from a common ancestor population that was divided when the Grand Canyon formed. If this hypothesis is correct, it would be an example of:A) allopatric speciation by dispersal
B) allopatric speciation by vicariance
C) sympatric speciation by vicariance
D) sympatric speciation by dispersal

Speciation is the process by which new species arise from an existing species.
Speciation are broadly classified as; Allopatric speciation, sympatrc speciation speciation and parapatric speciation.
Allopatric speciation occurs when groups of individual of a given population is separated by a geographical barrier like mountain, river etc.
Parapatric speciation occurs when group of individuals of same species occupy different niches in the same habitat that result in occurrence of new traits.
Sympatric speciation occur when individual of a population do not recognize each other as potential mates.

In the given situation, the antelope ground squirrel were separated by the Grand Canyon which is geographical barrier.
Again the population was divided by the formation of Grand Canyon and not because the populations migrated to a diverent locations.
So this example is of Allopatric Speciation by vicariance.