Respuesta :
Answer:
The correct answer would be geographic isolation.
Geographic isolation is a type of isolation in which organisms of the same species are prevented from exchanging genetic due to the separation of the organisms through physical structures such as a river, mountain et cetera.
For example, the squirrels were separated through the Colorado River.
Over generations, organisms evolve new traits as an adaptation towards different habitats.
For example, the squirrels evolved different ears, tails, and body type.
Over several generations, accumulation of genetic variations makes the two populations so different that they can not interbreed with each other.
Thus, the populations evolved into different species.