The most accurate response that illustrates the correlation between a specific trait (beak shape) and competitive advantage in a particular environment is:
Only individuals that had beaks well-adapted to eat food resources found on an island survived and reproduced on that island.
This response effectively captures the essence of natural selection, where the trait of beak shape directly relates to the finches' ability to access food resources, thereby influencing their survival and reproductive success in the specific environmental conditions of the Galápagos Islands.