Logical Reasoning

PT110 · S3 · Q24 Ringtail opossums are an Australian

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Ringtail opossums are an Australian wildlife species that is potentially endangered.

Conclusion (concluded)

The native ringtail opossum population is endangered not by a scarcity of food, as had been previously thought, but by non-native predator species against which the opossum had not developed natural defenses.

Evidence

A number of ringtail opossums that were orphaned and subsequently raised in captivity were monitored after being returned to the wild.

Seventy-five percent of those opossums were killed by foxes, a species not native to Australia.

Evaluate

This conclusion has two claims, one of them causal and the other anti-causal. We can reverse engineer from the conclusion what causal mystery they are trying to solve.

Curious Fact: Why is the ringtail opossum population endangered?

Author's Explanation: It's due to non-native predator species, such as foxes, rather than a scarcity of food.

To strengthen this argument, we can either rule out an alternate explanation (such as food scarcity) or increase the plausibility that non-native predators are indeed a significant threat.

Goal

Let's find an answer that either undermines the food scarcity theory or strengthens the idea that non-native predators, like foxes, are a significant threat to the ringtail opossum.

24.

Which one of the following, if true, most strongly supports the conservationists' argument?

There are fewer non-native predator
Opposite (if anything)
The number of non-native vs. native predator species doesn't affect whether non-native predators are the main threat over food scarcity. The argument is concerned with impact, not quantity. But even if we equated number with impact, this is diminishing the importance of non-native predators, which works against the author's hypothesis that non-native predators are the reason for the opossum's endangered status.
5% picked this
Foxes, which were introduced into
Irrelevant Comparison
Foxes' success in adapting compared to other non-native species doesn't address whether predation by non-native species like foxes is the primary danger to the ringtail opossum.
1% picked this
The ringtail opossums that were
No Impact
The diet of captured opossums being similar to that of wild ones does not address the argument about the primary cause of their endangerment, which is focused on predation. It might feel like this is ruling out an alternate explanation -- "the captive opossums who were released into the wild didn't die because they had been raised on an atypical diet while in captivity" But we already know why those released opossums died (they were eaten by foxes). And the conclusion isn't specifically about the opossums in captivity; it's about the endangered status of that species overall.
14% picked this
Few of the species that
No Impact
This can be re-worded as "most species competing with the opossum for food are non-native". That sort of sounds like, "non-native species are a problem for the opossum" but the hypothesis is specifically about non-native predators, animals who eat opossums, not animals who eat the same food as opossums.
6% picked this
Correct
Ringtail opossums that grow to
Why this is right
This provides support for the claim that non-native predators, like foxes, pose a significant threat. If opossums raised in the wild fare no better against foxes than those raised in captivity, it suggests the issue isn't about a lack of natural defenses developed in the wild but rather the overwhelming threat from non-native species. Someone might have objected to this argument by saying, "the fact that foxes killed most of the released opossums doesn't show that foxes are a big threat to the species -- it just shows that foxes are a big threat to sheltered opossums who didn't know how to act in the wild." This answer shuts down that line of objection by saying, "No, the wild opossums are equally bad at defending themselves from fox attacks."
Skill tested: Strengthen · how this choice captures the argument's function is the move to repeat next time.
73% picked this

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