Darwin's finches are an example of adaptive radiation, the evolution of an animal or plant group into different types adapted to specialized ways of life. Their common ancestor arrived on the Galapagos about two million years ago. Over time, Darwin's finches have evolved into 15 recognized species differing in body size, beak shape, song and feeding behavior. The picture here shows finches with four different types of beaks.

What statement best represents how one species of finches became many?

A. In order to survive, the finches with different beaks flew to the island with the best food source for each beak type. Over time they evolved into different species.

B. The finches became isolated from one another on different islands. Because each island was different and presented different food sources, those finches with the beak type best fit for each island ecosystem survived to reproduce, over time evolving into different species

C. The finches became isolated from one another on different islands. Because each island was different and presented different food sources, those finches with the beak type best fit for each island ecosystem survived to reproduce, over time evolving into different species

D. The finches became isolated from one another on different islands. Finches developed the beaks that would best help them survive, over time evolving into different species.