A Population of Ground Squirrels Is Separated by a Glacier

Multiple Choice

A population of ground squirrels is separated by a glacier.Changes in which of the following would most likely result in reproductive isolation if the two populations came into contact several generations later?

A) A change in the fur colour of one group.
B) A change in the diet of one group.
C) A change in the gene encoding of a receptor on the egg-cell surface in one group.
D) A change in the alarm call of one group to warn of predators.