A) is true, because this species has variation, a critical requirement for the evolution of adaptations by natural selection.
B) is false, because females with orangish throats could still have more offspring that live to reproduce than females with reddish throats.
C) is false, because there is no guarantee that females with reddish throats are the best for the long-term preservation of this species.
D) could be true or false, because we cannot tell without knowing whether reddish females outnumber orangish females in this species.

A) evolved function.
B) genetics and development.
C) evolutionary history.
D) adaptive value.

A) can be proven.
B) is an explanation based on limited evidence that can be tested.
C) is mutually exclusive to any other potential explanations.
D) is a basic principle that can be applied widely.