Use the information below to answer the next two questions. Natural Selection can sometimes be observed in only a few generations. Darwin’s finches are 13 distinct species of birds that live on the Galapagos islands. Each species has adapted over time to specific food sources, habitats, and behaviors. Medium ground finches have a stubby beak and eat mostly small to tiny seeds. The larger birds with larger beaks can eat a variety of different sized seeds, while the smaller birds with smaller beaks cannot crack open larger seeds. 

Based on the information provided - What variation exists in the population of medium ground finches?
a. Fly at different speeds
b. Different beak sizes
c. Different colored feathers
d. Different food sources

b. Different beak sizes