Once upon a time there was an island called Flores in the eastern part of Indonesia. The island was formed from volcanic activity millions of years ago, and in the center of the island there still exists a somewhat active volcano. Surrounding the volcano there is a forest filled with trees, several small lakes, and a long stretch of savannah which is basically a large green field of long grass with some bushes and flowers and hills.

On this island there was a species of frog who mostly lived in one of the blue lakes, and the frogs were bright blue with long webbed feet and tiny eyes – the Blue Swimmers. One day as they were swimming around, they felt a rumbling in the water. A few of them popped their little eyes over the surface of the water in time to see that the island volcano was erupting. Hot lava splashed down into their lake. Not a single frog was killed. But when the lava cooled, it seemed that the hardened lava had formed a large island in the center of the lake, and the lake was now completely divided into two smaller lakes.

Half the frogs were trapped in the lake on one side, and the other half of the frogs were now trapped in the other lake.

Down below in the lake population of Blue Swimmers, a small group of Dancing Blue Swimmers over time starts becoming an exclusive group that chooses to only mate with each other, and though the Dancing Blue Swimmers live happily with the rest of the Blue Swimmer population, they no longer mate with them.

Over time, this Dancing Blue Swimmer community has become reproductively isolated from its ancestors, and if a scientist were studying this group they would probably say that they had evolved into their own species.

This would most accurately be called:

a) Genetic drift
b) Allopatric speciation
c) Sympatric speciation
d) Natural selection