QUESTION TYPE: Weaken
CONCLUSION: We shouldn’t feed animals GMO plants.
REASONING: Rats that ate GMO potatoes for 30 days had two problems. A control group fed a normal diet of foods did not develop these problems.
ANALYSIS: In a scientific experiment, you should keep variables the same, except the variable you’re testing. The stimulus fails to do that. One group of rats eats only GMO potatoes. The other group eats “a normal diet”. I’m pretty sure rats normally eat more than potatoes.
So the intestinal deformities could have been caused by the fact that rats weren’t eating their normal diet, rather than because the potatoes were GMO.
- CORRECT. This shows that the first group wasn’t eating normal food. Maybe they got sick because rats don’t digest potatoes well, and because they were missing foods they’d normally eat. Imagine eating nothing but potatoes!
- You must always take answer choices at their weakest on weaken questions. “Tended to eat more” has a wide range of meanings. At it’s weakest, it could mean that 51% of the rats ate 2% more potatoes at the start of the month. That doesn’t tell us anything. (Though even if we took a stronger version of this answer, I’m not sure how it would weaken the argument!)
- This affects nothing. The stimulus is talking about rats that developed intestinal deformities. The rats in the experiment were not the ones who had intestinal deformities at birth.
- You might think that this shows that regular potatoes would have the same effect. But food is more than its nutritional value. “Has arsenic” is not a nutritional value – but you shouldn’t eat an apple laced with arsenic! Maybe GMO potatoes have similar non-nutritional, poisonous effects.
- You don’t have to be able to explain something in order to warn against it. If 100% of people who eat a certain food die, then it’s valid to say “don’t eat it!!”, even if you don’t know why people die.
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