During Drought Years on the Galapagos, Small, Easily Eaten Seeds

Multiple Choice

During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large, hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should one expect to result from natural selection?

A) Small birds gaining larger beaks by exercising their mouth parts.
B) Small birds mutating their beak genes with the result that later-generation offspring have larger beaks.
C) Small birds anticipating the long drought and eating more to gain weight and, consequently, growing larger beaks.
D)
More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks.
E) Larger birds eating less so smaller birds can survive.