Two of Darwin's finches display a character displacement when they occur as sympatric species. Which of the statements correctly describes the distribution of break depths in these species.
a. Both species have the same size beaks on Los Hermanos Island.
b. Both species have the same size beak on Santa Maria Island.
c. The two species have the same beak sizes, but only when they occur on the same island.
d. The two species have different beak sizes, but only when they occur on the same island.