PrepTest 158

Even if rainwater accounts for only a tiny percentage of the total water in Crystal Bay, we'd still expect Crystal Bay's pollution levels to go down when the pure rainwater fell directly to the bay. This answer could explain why Crystal Bay's pollution levels don't fall much after rain, but it doesn't explain why the pollution levels increase.

Argument or Facts:
Facts

Question Type:
Paradox

Stimulus Summary:
Pollution levels at the so-called Crystal Bay are highest after rainfall. But rainwater is pure, so we'd expect that rain would dilute the polluted seawater.

Strategy Overview:

1. Argument or facts? Always a set of facts
2. Identify what is strange, discrepant, surprising, or paradoxical in the passage
3. Anticipate additional facts that could be added that could make the passage make more sense
4. Use anticipation to find the answer choice that, if added to the set of facts in the passage, would make the discrepancy/paradox make more sense

Answer Anticipation:
We want to find the answer choice on Paradox questions that would make the discrepant, surprising, or paradoxical situation make more sense. To that end, it helps to clarify why the situation is discrepant, surprising, or paradoxical in the first place. For this passage, it's surprising that Not-So-Crystal Bay would be more polluted after rainfall. After all, rainfall is pure, so we'd expect the rain to dilute the bay's dirty water, making it less polluted.

Once we've clarified why the situation is surprising, we can zero in on how the passage makes this sound surprising. This stimulus draws our attention to rainfall going directly into the sea and diluting the seawater. Which it certainly could do. But the passage wants us to only focus on rain falling straight into the sea. But ... could rainwater reach Crystal Bay by other means, like falling on land and being transported into the bay? Would this allow the rainwater to accumulate toxins, thus polluting Crystal Bay?

So we should look for an answer choice that shows us how rainwater could make Crystal Bay more polluted, even if the rainwater is initially pure as it falls.

Answer Choice Explanation:
As predicted, this answer choice shows that rainwater can reach Crystal Bay through means other than direct rainfall. If most rainwater that winds up in Crystal Bay takes a circuitous path through pesticide-treated fields, that would explain why the pollution levels tend to go up following rain. Rather than falling into Crystal Bay as this passage discussed, the rainwater can become less pure and increase Crystal Bay's pollution levels if it instead picks up some pesticides from fields that carry it to the bay.

Key Takeaway:
On Paradox questions, the correct answer often deals with an external influence not mentioned by in stimulus. In this case, that influence was the land pollution that could be brought to Crystal Bay by rainfall. After you notice the influence the passage wants you to focus on (in this case, rain falling directly to the ocean), you can start to brainstorm some alternative influences that could help to resolve the paradox.

Even if rainwater is mostly evaporated ocean water, the passage tells us the rainwater is pure. So, if the rainwater falls directly into Crystal Bay, we'd still expect the rain to dilute Crystal Bay and reduce its pollution levels. Therefore, this answer does not explain why Crystal Bay's pollution levels are higher following rainfall.

Even if the primary source of Crystal Bay's pollution is beachgoers' behavior, we'd still expect Crystal Bay's pollution levels to go down if rain fell directly into the bay and diluted the extant pollution. In fact, since beachgoers typically do not go to the beach on rainy days, this answer choice makes Crystal Bay's high post-rain pollution levels all the more inexplicable.

This answer choice shows that there's a similar pattern of high post-rain pollution in other oceans. But identifying a pattern is not the same thing as explaining the causes of that pattern. So, this answer choice doesn't address the fundamental mystery the passage presents: why wouldn't the rainfall dilute and reduce the pollution levels in Crystal Bay?