Explanation

11) Choices B and C are correct. The question asks how the two studies differed. Choice A is incorrect: In the guppy study, the more likely victims are the hungry
guppies who “feed with greater intensity” and are, therefore, more active than well- fed guppies. Choice B is correct: The passage states that “well-fed guppies are more alert for predators and are consequently less likely to be killed” and that “anesthetized,” or less alert, tadpoles “were less likely to be captured by dragonfly larvae.” Choice C is correct: In the guppy study the subjects were well fed, while in the tadpole study the subjects were anesthetized; this latter condition is much less unlikely to occur in the wild.

12) The passage states that benefits of increased antipredator behavior “are not easily demonstrated”; in this context, “shown” is the closest synonym, so Choice C is correct.