Explanation
Correct answer: C.
Choice C is the best answer because it most logically completes the text’s discussion of researchers’ observations of white-necked jacobin hummingbird females that retain blue head plumage into adulthood. The text indicates that even though adult males show a clear preference in mate selection for adult females with drab green feathers, a significant percentage of adult females (28%) retain blue head plumage. Critically, the text also notes that the mating advantage conferred on adult females by green head plumage is offset by the fact that when competing for resources, adult males behave more antagonistically toward green-feathered adult females than toward blue-feathered ones. Given this discrepancy in the males’ behavior, it is reasonable to hypothesize that the occurrence of blue head plumage in adult females is driven by factors not associated with mate attraction—specifically, reduced antagonism during resource competition.
Why the other choices are wrong
Choice A
Choice A is incorrect because the antagonistic behavior discussed in the text is that displayed by adult male jacobins toward blue-feathered and green-feathered adult females, not toward juveniles. The text doesn’t discuss the behavior of adult males toward juveniles.
Choice B
Choice B is incorrect. Although the text cites the current percentage (28%) of female white-necked jacobin hummingbirds that retain blue plumage into adulthood, it doesn’t make predictions about future changes in the proportion of blue to green plumage in this species or provide information supporting such a prediction.
Choice D
Choice D is incorrect because the text doesn’t discuss the perceptual abilities of green-feathered adult females or whether they can distinguish between adult males and blue-feathered adult females. Instead, the text focuses on adult male behavior—namely, mate selection and antagonism toward adult females.
Student discussion
shahdia2911 1 likes
Males aren't attracted to blue head plumage hummingbirds, but they have an advantage for food as males are less aggressive towards them. so, since blue feathers don't help with attracting mates, they exist for other reasons (like resource advantages).