PrepTest 139

Incorrect. While most weren't, some were, as the stimulus notes that the birds ate "many mosquitoes." While this answer might explain why the mosquito population didn't decline as much as expected, it doesn't explain why it actually went up ("opposite of its intended effect").

Incorrect. Similar to (A), this answer would explain why the population didn't go down as much as expected, but it doesn't explain why it actually went up despite some of the birds eating many mosquitoes.

Correct. Argument or Facts:
Facts

Question Type:
Paradox

Stimulus Summary:
Problem - Too many mosquitoes in a resort area
Solution - Plant trees to attract birds to eat the mosquitoes
Unexpected outcome - The birds showed up and ate the mosquitoes, but their population went up

Answer Anticipation:
This stimulus falls into a common pattern—a problem is raised, a solution is offered (and implemented), and an unexpected outcome occurs. In this case, the solution actually made the problem worse.

Whenever a solution is implemented, there's a change that happens. Not all effects of a given change can be predicted, and so to explain the unexpected outcome noted, we need to find another unexpected outcome of the change that could itself cause the one noted in the stimulus. So here, we need to find something that planting these trees or attracting these birds did that would result in more mosquitoes. That's wide open, but having it framed this way should help us find the correct answer.

Answer Explanation:
If the mosquitoes have two sets of predators—birds and other insects—and the birds took out the other predators, that could explain how the mosquito population went up despite having a new predator around—the old predator wasn't eating as many of them anymore.

Key Takeaway:
Paradox questions will frequently feature a change/solution with an unexpected outcome. When this happens, the correct answer itself generally brings up another unanticipated effect of the change that can connect the action taken and the unexpected outcome.

Incorrect. If anything, this makes the paradox worse—if the weather should have reduced the mosquito population and they were being eaten by birds, how did the mosquito population increase?

Incorrect. First, this answer is about what they "tend" to do—not what happens when a new predator is introduced. Second, there's no indication that this was part of a cyclical uptick.