Question

many male tanager finches exhibiting carotenoids, pigmented molecules that are associated with better oxidative. coloration tends to be especially saturated in male birds, and females can establish who confer health benefits, the deeply saturated colors commonly serve as communication what is known as an honest signal of a bird’s overall fitness to potential mates. however, ornithologist allison j. shultz and others have found that within the several species of the tanager genus ramphocelus use microstructures in their feathers to manipulate light, creating the appearance of deeper saturation without the necessity having to maintain a carotenoid - rich diet. these findings suggest that
15 mark for review
which choice most logically completes the text?
a individual male tanagers can engage in honest signaling without relying on carotenoid consumption.
b feather microstructures may be less effective than deeply saturated feathers for signaling overall fitness.
c scientists have yet to determine why tanagers have a preference for mates with colorful appearances.
d a male tanager’s appearance may function as a dishonest signal of the individual’s overall fitness.

Explanation:

The text discusses tanagers using microstructures to appear more saturated without extra carotenoids, relating to honest signaling of fitness. Option A: The text says they use microstructures, not rely on carotenoid consumption for signaling, so A fits as it completes the idea that male tanagers can signal honestly without relying on carotenoid intake. Option B: The text doesn't compare microstructures and saturated feathers' effectiveness. Option C: The text is about how they signal, not why they prefer colorful mates. Option D: The text is about honest signals, not dishonest ones. So A logically completes the text.

Answer:

A. individual male tanagers can engage in honest signaling without relying on carotenoid consumption.