PrepTest 108, Section 2, Question 9
Very powerful volcanic eruptions send large amounts of(81 more words not shown)
In evaluating the support given(19 more words not shown)
- Amodern monitoring equipment(11 more words not shown)
- Bthe abnormal weather(9 more words not shown)
- Ctemperatures in Sicily(7 more words not shown)
- Dthere were any(11 more words not shown)
- Esubsequent eruptions of(11 more words not shown)
Reading the argument
The timing makes Mount Etna a possible explanation. It erupted in 44 B.C., and China had a dim sun and summer frosts the following year. Volcanic ash can block sunlight and produce colder weather. But was Etna the volcano responsible?
At first, we might wonder whether something other than volcanic ash caused the Chinese weather. The conclusion makes a narrower claim: if ash caused those conditions, then Etna's ash must have traveled a great distance. Even granting the “if,” we still need to know whose ash it was.
What we’re looking for
What if a different volcano erupted much closer to China around the same time? Then volcanic ash could explain the weather without Etna's ash making that whole trip. That's what I'd want to investigate. The question asks which piece of information would be most useful for evaluating the argument, so look for a question whose answer helps us distinguish Etna from that alternative.
Working the answers
- A
Modern equipment's ability to trace ash doesn't tell us where the ash in this ancient event came from. We would need relevant evidence about that eruption, not merely a statement about what today's equipment can do. This question doesn't settle the proposed connection between Etna and China.
- B
A long cold spell might fit the description of the effects of volcanic ash. But the argument already makes its claim conditional on ash causing the Chinese phenomena. Knowing the weather lasted a year would not distinguish ash from Etna from ash from another eruption.
- C
Cold weather in Sicily could help connect Etna to local effects. It would not show that Etna's ash traveled all the way to China. The distance is the disputed part: evidence that the eruption affected its own region doesn't establish that it caused the distant conditions.
- DCorrect
An eruption near China would provide another possible source of the ash. If there was one at the relevant time, we would have reason to question the claim that the Chinese weather required Etna's ash to travel so far.
If there wasn't one, that particular alternative would be less available, which would make the Etna explanation more credible. That still wouldn't prove Etna caused the weather; an evaluation answer needn't settle every uncertainty. It needs to give us information that matters to the inference, and this does.
- E
Later eruptions don't identify the source of the ash associated with this earlier event. Etna might have erupted just as powerfully afterward, but we would still need to connect the 44 B.C. eruption to the Chinese weather the next year. Matching the strength of a later eruption doesn't provide that connection.
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