Final answer:
Cryptic coloration is the defense mechanism that helps a prey species avoid detection by a predator by allowing it to blend into its surroundings.
Step-by-step explanation:
The feature that helps a prey species avoid being detected by a predator is b. Cryptic coloration. Cryptic coloration allows an organism to blend in with its surroundings, making it less visible to predators. This form of camouflage is a passive defense strategy, as opposed to active strategies like those involving toxins or stinging. In contrast to cryptic coloration, Batesian mimicry involves a non-toxic species adopting the look of a toxic species to ward off predators, while Mullerian mimicry involves multiple toxic species sharing similar warning coloration to reinforce the avoidance behavior in predators. Additionally, Secondary compounds are chemical substances produced by plants to deter herbivory but don't have to do with visual detection directly.