PrepTest 45, Section 2, Question 12
Biologists have noted reproductive abnormalities in fish that are immediately downstream of paper mills. One possible cause is dioxin, which paper mills release daily and which can alter the concentration of hormones in fish. However, dioxin is unlikely to be the cause, since the fish recover normal hormone concentrations relatively quickly during occasional mill shutdowns and dioxin decomposes very slowly in the environment.
Biologists have noted reproductive abnormalities in fish that are immediately downstream of paper mills. One possible cause is dioxin, which paper mills release daily and which can alter the concentration of hormones in fish. However, dioxin is unlikely to be the cause, since the fish recover normal hormone concentrations relatively quickly during occasional mill shutdowns and dioxin decomposes very slowly in the environment.
Biologists have noted reproductive abnormalities in fish that are immediately downstream of paper mills. One possible cause is dioxin, which paper mills release daily and which can alter the concentration of hormones in fish. However, dioxin is unlikely to be the cause, since the fish recover normal hormone concentrations relatively quickly during occasional mill shutdowns and dioxin decomposes very slowly in the environment.
Biologists have noted reproductive abnormalities in fish that are immediately downstream of paper mills. One possible cause is dioxin, which paper mills release daily and which can alter the concentration of hormones in fish. However, dioxin is unlikely to be the cause, since the fish recover normal hormone concentrations relatively quickly during occasional mill shutdowns and dioxin decomposes very slowly in the environment.
Which one of the following statements, if true, most seriously weakens the argument?
Some of the studies that show that fish recover quickly during shutdowns were funded by paper manufacturers.
The rate at which dioxin decomposes varies depending on the conditions to which it is exposed.
Normal river currents carry the dioxin present in the river far downstream in a few hours.
Some of the fish did not recover rapidly from the physiological changes that were induced by the changes in hormone concentrations.
The connection between hormone concentrations and reproductive abnormalities is not thoroughly understood.
Explanations
I love this question. It's a doozy! And it's a great example how you can subtly weaken an argument.
Start with the author's conclusion: it's unlikely that dioxin from paper mills cause the fish's hormonal abnormalities.
Next, ask yourself how the author justifies their conclusion. They cite two reasons:
(1) The fish recover quickly when the mills occasionally shut down.
(2) Dioxin decomposes very slowly in the environment.
The correct answer will increase the likelihood that the dioxin from the mills causes the abnormalities. The four wrong ones either won't affect the conclusion or will make it even less likely that dioxin is the culprit.
Let's see.
Nah. All this does is tell me that the premises might have come from a biased source, not that they definitely did (or that they're incorrect, for that matter—you can be biased and right at the same time).
Nope. Cool story bro, but we have a very specific environment where we're evaluating the dioxin. Its decomposition rate changing in other environments tells me nothing about this one.
Tough! But, yes. Follow me: Dioxin decomposes slowly. The fish recover quickly during mill shutdowns. So, during shutdowns, the fish recover quickly despite the dioxin still sticking around (due to its slow decomposition). If normal river currents wash the dioxin away, then the mill shutdowns would be less helpful to these fish, because the dioxin wouldn't be sticking around anyway.
No way. Cool story—"some" fish don't experience the same problem alleged in the passage, but this could literally mean one single fish. The rest still experience the alleged issues. Moreover, D doesn't address a premise of the argument, just the background information from the passage's first sentence. This doesn't affect the author's conclusion.
Nah. This doesn't affect the conclusion because it's more or less stated in the passage. We already know that we don't understand these fish hormonal issues and we're searching for an explanation. The author rejects the alleged explanation—dioxin—but this rejection doesn't change the fact that we still don't understand the cause.
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