The bird, Parus major, is commonly found in man-made habitats. During the summer these birds primarily feed on insects, and in the winter, when insects are scarce, they forage in gardens and bird feeders for seeds, nuts, and berries. Recently, climate change has led to a decrease in food available from gardens, and scientists have observed that the average beak length of the birds has increased.
Which of the following best explains the directional shift in beak length in these birds?A. Longer beaks allow the birds to better fend off predators. B. Longer beaks increase the fitness of the birds in wild habitats. C. Longer beaks allow the birds to better access seeds in bird feeders. D. Longer beaks decrease the fitness of the birds in wild habitats.