PrepTest 116, Section 2, Question 4
A study claims that the average temperature on(55 more words not shown)
Which one of the following(8 more words not shown)
- AAll large increases(10 more words not shown)
- BFive successive years(14 more words not shown)
- CRecord high temperatures(9 more words not shown)
- DRandom fluctuations in(9 more words not shown)
- EThe average temperature(11 more words not shown)
Reading the argument
Permanently? Five hot years seems like a short basis for that claim.
The study has evidence of high temperatures: every one of the last five annual averages exceeded any earlier annual average on record. But even if the warming were dramatic, why couldn't temperatures fall again later? A future ice age, for example, would undo the claim of permanence. I'm not predicting an ice age; I'm asking what rules out a later reversal.
The next sentence gives us a more immediate reason for caution. Even stretches of record-high temperatures lasting up to ten years are often just part of random fluctuations. A run of highs can therefore occur without establishing a lasting change. Our five-year run isn't automatically different.
What we’re looking for
The question asks what the information most strongly supports. I'd push back on the study: it has gone too far in treating these observations as proof of permanence. Be careful about the size of that objection, though. Showing that the study hasn't established its conclusion isn't the same as showing that a permanent increase is impossible.
Working the answers
- A
“All large increases” goes much further than the information. We learn that some extended runs of record highs are part of fluctuations. We don't get a complete history of large temperature increases or a rule placing all of them within ten-year periods.
- BCorrect
Five successive years of increasing annual averages need not mean a permanent increase. The passage explains that even longer stretches of record highs can belong to random fluctuations. So a five-year pattern doesn't always establish what the study takes it to establish.
This answer leaves room for lasting warming. Its point is that this sort of short run doesn't guarantee it. That's the supported objection to the study's reasoning.
- C
Why another five years? The passage gives no timetable for when the present run will end. Even the study's claim of a permanent increase wouldn't require a new record every year: temperatures could stay at a higher level without continuing to rise. C makes a forecast neither part of the passage supplies.
- D
The ten-year figure describes stretches of record-high temperatures that can be part of fluctuations. It doesn't tell us how long a fluctuation as a whole typically lasts. Nor does “up to ten years” establish that the typical duration is less than ten. D turns a description of possible high-temperature runs into an unsupported generalization about duration.
- E
The study could be wrong to infer permanence from five years without every temperature increase being random. A lasting warming process could exist alongside shorter fluctuations. E rules out every other kind of increase, which the passage never does.
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