LR Drill Set 14, Question 4
Zebra mussels, a nuisance when they clog the(55 more words not shown)
Which one of the following(15 more words not shown)
- AZebra mussels arrived(23 more words not shown)
- BIf the mussels(34 more words not shown)
- CThere is no(13 more words not shown)
- DThe algae on(23 more words not shown)
- EAny hazardous waste(26 more words not shown)
Reading the argument
The same mussels can clog a pipe and improve the water passing through another system. Those aren't incompatible effects.
The passage first describes the nuisance, then describes a useful application: mussels in bags filter water in chemical-plant discharge streams, removing algae and even some hazardous waste. We should keep the two roles separate rather than assume anything that is troublesome must have no benefits.
I initially wonder whether the hazardous material is in the algae the mussels eat. The passage doesn't specify that route precisely, though, so we shouldn't turn that guess into a fact. What it does establish is that the mussels remove some hazardous material from the discharge.
What we’re looking for
For the most-supported conclusion, I wouldn't force a precise prediction. We have a few facts about where the mussels are, what problems they create, and what they filter out. Test each answer against those facts. If an answer adds a claim, we need a reason that claim follows; being about the same animal isn't enough. We can make a supported inference without inventing an entire story about the mussels.
Working the answers
- A
We aren't told how the mussels reached the Great Lakes, whether they have natural enemies there, or whether they are displacing native clams. The passage describes their current effects. A supplies an entire history and ecological account beyond that evidence.
- B
This predicts the collapse of a pearl industry in another location. We have no facts about that industry's dependence on particular clams, whether the mussels would displace them, or whether they could be used for pearls. A prediction with several new links isn't supported by the description of filtering and clogged pipes.
- C
Clogging a pipe doesn't establish that the mussels cannot be mechanically scraped away. Removal could be possible but expensive or inconvenient. The word 'nuisance' doesn't turn the problem into an impossibility of mechanical clearing.
- D
The mussels clog the intake pipes. The passage doesn't say the algae they eat would also clog them if left uneaten. Algae could affect water quality without blocking a pipe. We can't transfer the mussels' stated effect to their food.
- ECorrect
Removing hazardous material from the water doesn't automatically make that material harmless. If the mussels take it in without transforming it, the hazard remains in the material they contain, so the contaminated mussels must themselves be treated as hazardous waste.
The condition matters. We might object that the mussels could process the material into something harmless. E explicitly sets that possibility aside with 'if they do not transform it.' It doesn't assert that harmless processing is impossible. It describes the consequence when the waste is removed from the discharge but remains hazardous within the mussels.
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