Which is an example of geographic isolation? a) a species of chipmunk becomes extinct because of a lack of food. b) two groups of albatross live on separate islands but commonly cross from one island to the other. eliminate c) a group of snakes is unable to cross a river and is separated from a group of snakes on the opposite side. d) one group of frogs mates in spring and another mates in fall, effectively isolating the two groups from breeding with each other.