While visiting the Galapagos Islands in 1835, Charles Darwin collected over thirteen different species of a type of bird called a finch. He later observed that the birds were similar in many ways but often differed in the size and shape of their beaks. Which statement BEST summarizes Darwin's explanantion for the different beaks he observed in these finch species?
A) The beaks changed so they could eat different foods.
B) The beaks of each finch species were the result of natural selection.
C) The size and shape of the beaks differed because of the effects of artificial selection.
D) The size and shape of the beaks differed because of different climates found on the islands.