Benkman's Experiment with Five Species of Birds of the Crossbill

Multiple Choice

Benkman's experiment with five species of birds of the crossbill species complex showed that each species' bill morphology had a positive correlation with its preferred pine cone, which also provided the highest survival rate of each bird type. What major conclusion did Benkman make in response to this evidence?

A) The crossbills' differences are due to past geographical isolation.
B) The crossbills are currently undergoing evolutionary divergence.
C) The crossbills that prefer the most common type of cone will eventually outcompete the others.
D) The crossbills are very flexible in the type of cone they can eat, leading to their success as a species.