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For stingrays, it's healthy to not have parasites.
For ecosystems, it's unhealthy for stingrays to not have parasites.
I think we know from common sense why it's healthy for an organism not to have parasites. So it feels like the burden of the answer choice lies more in explaining why not having parasites in stingrays is an indicator of a stressed (unhealthy) ecosystem.
Which one of the following, if true, most helps to reconcile the discrepancy indicated above?
During part of their life
Why this is right
How is a lack of parasites in stingrays an indicator of a stressed ecosystem? Well, shrimp and oysters are indicators of a stressed ecosystem, since they are environmentally vulnerable. And the parasites that show up in stingrays have always lived previously in shrimp or oysters. So if parasites stop showing up in stingrays, it suggests that there weren't any shrimp or oysters around to get the parasites through that part of their life cycle. And if there aren't shrimp or oysters around, then it suggests that some environmental stressor has depleted populations of environmentally vulnerable organisms. Quite a reach, huh? No one said these correct answers have to be super convincing -- just "most helpful" out of the available options.
Skill tested: Paradox · how this choice captures the argument's function is the move to repeat next time.
69% picked this
A stingray is a free-ranging
This doesn't give us a way to explain why it's a bad sign for an ecosystem if stingrays don't have parasites.
2% picked this
A parasite drains part of
This answer offers a reason why a stingray without parasites would be healthier than a stingray with parasites. That part of the paradox was already pretty self-justifying, from common sense. This answer isn't doing anything to tackle the more surprising claim, which doesn't have a common sense explanation -- why is it a bad sign for an ecosystem if its stingrays don't have parasites?
5% picked this
An ecosystem can be considered
This doesn't give us a way to explain why it's a bad sign for an ecosystem if stingrays don't have parasites. It's also almost never the case that the correct answer to Strengthen, Weaken, or Paradox would be as weak as "X can be considered Y" (or as weak as some, sometimes, may, might, not always)
15% picked this
Since the life of parasites
This doesn't give us a way to explain why it's a bad sign for an ecosystem if stingrays don't have parasites. If it's doing anything, it's explaining why parasites aren't lethal for stingrays.
9% picked this
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