PrepTest 127, Section 2, Question 4
The song of the yellow warbler signals to(104 more words not shown)
The argument makes which one(4 more words not shown)
- AThe core areas(12 more words not shown)
- BWarblers are the(14 more words not shown)
- CThere are no(12 more words not shown)
- DWarblers often share(21 more words not shown)
- EThe core areas(12 more words not shown)
Reading the argument
The ordinary song marks a yellow warbler's territory, but it doesn't keep every other yellow warbler out. Others may still feed around part of that area. Preventing a takeover is different from preventing any use of the food.
During molting, the bird sings a special song. Other yellow warblers stay out of its smaller core territory, which helps a bird that can fly only short distances. So far, that tells us about competition from other yellow warblers.
Then the conclusion says there is no competition for food. What about other kinds of birds? What about rodents or other animals that might eat the same food? Keeping yellow warblers away doesn't necessarily keep every competitor away.
What we’re looking for
We need an assumption the argument depends on. I'd look for the missing restriction on competitors: the food cannot also be contested by animals the evidence hasn't ruled out. Otherwise the molting bird could avoid competition from its own species and still have to compete for its food.
Working the answers
- A
The exact quantity of food isn't what establishes the absence of competition. There might be abundant food, or too little to sustain the bird, without any other animal competing for it. The argument doesn't need the amount to be exactly enough for one warbler.
- B
Other molting birds could also use songs to claim core feeding areas. Nothing in the reasoning depends on yellow warblers being unique in that behavior. What matters is whether other birds compete for the yellow warbler's food, not how those birds claim their own territories.
- CCorrect
This excludes other birds as food competitors. If another kind of bird competed for the same food, the fact that yellow warblers stay out would not establish freedom from competition. C addresses a necessary part of the gap we noticed: the argument rules out members of one species and then concludes there are no competitors.
- D
Birds that eat different insects or seeds need not compete for the warbler's food, even if they share the area. But the argument doesn't require that such sharing happen often. It requires the absence of food competition, which is a different claim.
- E
The core territories could vary in size without changing this reasoning. A larger bird might have a larger core area, for example. Equal territory size doesn't establish that competitors stay away, and the argument doesn't depend on that equality.
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