Two separate species of squirrels have evolved after being separated by the Colorado River's erosion of the Grand Canyon. What type of speciation has occurred here?

A. Allopatric Speciation

B. Sympatic Speciation

C. Disruptive Selection

D. Group Behavior

Option A

Explanation:

In this case the two species of squirrels have evolved when their combined population got divided into parts and was separated as a cause of natural calamity i. e Colorado River's erosion of the Grand Canyon, thereby forced to live in two different geographies and hence evolve differently from each other. The two geographies mentioned above remain disconnected by any natural barrier thereby restricting successful mating of the two population groups of squirrels.

hence, option A is correct