The red-eyed cowbird breeds by parasitizing the nests of

The red-eyed cowbird breeds by parasitizing the nests of orioles, among other birds. The cowbird lays its eggs in the orioles' nests while the female orioles are out searching for food. The cowbird has evolved certain traits and behaviors to ensure the success of its deception: It throws one oriole egg out of the nest for every one of its own eggs that it lays therein, and it has evolved an egg coloration similar to that of the oriole. An oriole whose nest has thus been parasitized will subsequently incubate and rear the cowbird chick, unaware of the cowbird's ploy.
Which of the following conclusions can most properly be drawn from the information above?

a. The stability of oriole populations is threatened by the behavior of red-eyed cowbirds.

b. The oriole does not possess any numeric ability.

c. The stability of red-eyed cowbird populations depends on the proximity of nesting orioles.

d. The red-eyed cowbird's behavior is not learned.

e. Scientists are unable to distinguish between a red-eyed cowbird egg and an oriole egg based solely on visual examination.