(A) contrasting the role of domination and courtship in determining the evolution of bird plumage
(B) illustrating the effectiveness of a particular approach to categorizing various evolutionary innovations
(C) documenting the origins of a currently accepted scientific theory about food and courtship
(D) proposing a new explanation for the evolutionary reasons behind the ornamentation of male bird plumage
(E) showing that physical adaptation plays an integral role in contributing to species identification of birds