Assertion: Darwin's finches show a variety of beaks suited for eating large seeds, flying insects and cactus seeds. Reason : Ancestral seed-eating stock of Darwin's finches radiated out from South American mainland to different geographical areas of the Galapagos Islands, where they found competitor-free new habitats.

Step-by-step solution

Darwin finches are an excellent example of the way in which the species gene pools have adapted in order for long term survival via their offspring. Finches were formed due to divergent evolution (adaptive radiation) to avoid interspecific competition. The common birds of Galapagos islands, the finches were markedly different from the finches of main land. The closely related species of finches had beak of different shapes and sizes and were adapted for feeding on completely different diets.