PrepTest 143, Section 4, Question 4
In polluted industrial English cities during the Industrial(24 more words not shown)
Which one of the following,(7 more words not shown)
- AScientists theorize that(9 more words not shown)
- BCertain measures help(18 more words not shown)
- CFor many plant(10 more words not shown)
- DBlack spot and(12 more words not shown)
- EBlack spot and(17 more words not shown)
Reading the argument
The diseases disappeared. Why blame the air pollution?
Air pollution is one possibility, but the same cities could have experienced other changes. What if water pollution killed the diseases? What if the roses and sycamores died, leaving the diseases without plants to infect? Those aren't facts we're adding to the passage. They're possibilities showing why disappearance in a polluted city doesn't, by itself, identify the cause.
What we’re looking for
We need to strengthen the proposed explanation. A useful comparison would be similar towns without the air pollution where the diseases kept occurring. That would help connect the disappearance specifically to the air pollution. We don't need to prove the cause beyond all doubt, but we do want evidence that helps separate this explanation from the alternatives.
Working the answers
- A
Plants resisting air pollution doesn't tell us why these diseases disappeared. The plants and the diseases infecting them are different things. A gives us a theory about how some plants cope with pollution without connecting pollution to the disappearance of black spot or tar spot.
- B
We aren't choosing a treatment for an infected plant. General information about prevention and the difficulty of eliminating an infection doesn't tell us what happened in these cities. B neither says a preventive measure was used there nor links the diseases' disappearance to air pollution.
- C
Not knowing pollution's effects on many plant species doesn't supply evidence about these two diseases. Scientists could lack information about other plants while having good evidence about roses and sycamores. C leaves the proposed causal link untested.
- DCorrect
This gives us a comparison over time: when the air became less polluted, the diseases returned. That is what we might expect if air pollution had been keeping them away.
My initial thought was to compare polluted towns with otherwise similar unpolluted towns. D instead compares the cities when their air was more polluted with those cities when it was less polluted. The diseases change along with the proposed cause. Other explanations could still be possible, but this repeated relationship gives the air-pollution explanation more support.
- E
Even if no other plant diseases disappeared, we still need to know why these two did. Perhaps air pollution affected these diseases specifically, or perhaps something else did. The fact that they were the only ones to disappear doesn't decide between those explanations.
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