Ants sometimes live in hollow places in the roots of a certain orchid species. Those orchids of that species that house ants are far healthier than those that do not. Since the ants store organic matter in the orchids’ roots, an explanation for the superior health of the orchids that house ants is that the organic matter stored by the ants provides those orchids with additional nutrients.

Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that ants are more likely to live in healthy orchid species because the ants store organic matter, thereby providing the orchids with additional nutrients.

Notable Assumptions
The author assumes that the organic matter brought by the ants are *causing* the orchids to be healthier. It could be equally true that healthy orchids attract ants to store their nectar (or some other variable).
The author also assumes that the ants’ presence does not harm the orchid in other ways.

A
Microscopic organisms that are present in the orchids’ roots break down the organic matter stored there by the ants.
If anything, this strengthens the link between organisms, bolstering the health of orchids. Thus, this does not weaken the argument.
B
The nutrients present in the organic matter stored by the ants are the same as those present in the soil in which the orchids are found.
While this suggests that the ants may not provide *unique* nutrients, it does not explain why the orchids are healthier. You have to make some unwarranted assumptions for this to work.
C
The ants that live in hollow places in the roots of orchids prey on an insect species whose members eat the orchids’ roots.
While this may look unrelated, it provides another explanation for *why* orchids with ants are healthier. If the ants hunt a species prone to eating the orchid’s roots, it explains the orchid’s improved health.
D
The ants that live in hollow places in the roots of orchids do not play a role in pollinating the flowers of the plant.
It does not matter whether the ants pollinate the plant. This does not provide an alternative explanation or weaken the argument.
E
Most plant species whose roots, stems, or leaves harbor insects are more prone to disease and rot than are other plants.
This is not specific enough to be applied to the ants and orchids. Also, it does not address why the orchids are healthier.

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Winchester Township cannot afford to keep its several small branch libraries supplied with a wide selection of current books. However, if the branch libraries were closed, then Winchester could afford to open one large library, which could carry broader and more current selections. Thus, Winchester would better meet its residents’ needs by closing its small branch libraries and opening one larger, well-supplied library.

Summarize Argument
The author believes that Winchester Township should close its smaller branch libraries to create one larger, and better stocked, library to better meet residents’ needs. This is because the town cannot afford to keep several of the smaller libraries well stocked, but could afford to do so if they had one larger library.

Notable Assumptions
The author assumes that the selection of books available outweighs all other factors for meeting their residents’ needs. Perhaps a single location will make the library unavailable for many residents.

A
Many Winchester residents never use the branch libraries because of the irregular hours each branch keeps.
If anything, this strengthens the argument because it suggests that the residents would not really mind if the branch offices close.
B
Most Winchester residents have complained about the selection of books at the branch libraries.
Just because most residents have not complained about the selection of books, that does not undermine the reasoning that a larger selection would better meet the residents’ needs.
C
The only possible site for a new library is not readily accessible to most Winchester residents.
This directly calls out the author’s key assumption: that moving the library to a single location won’t have severe consequences. If the new location is not accessible, then it may not better meet residents’ needs.
D
It would cost Winchester a significant amount of money to build a larger library.
This is pretty much implied in the stimulus. This argument is about the *effectiveness* of the plan, not the monetary cost
E
Each of Winchester’s branch libraries attempts to cater to the tastes of the residents of the entire township.
While this may explain why they have limited selections, it does not weaken the claim that having a single well-stocked library would better meet residents' needs.

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The sculptor Barajas died before she could even begin sculpting the statue called Sonora. However, because Sonora was sculpted by Barajas’s assistants, working from three sketches Barajas drew in preparing to create the statue herself, the statue probably looks very much like it would have looked if she had lived to complete it.

Summarize Argument

The author argues that the statue “Sonora” looks very much like what it would have had its original sculptor, Barajas, lived to complete it. This is because Sonora was scrupled by Barajas assistants, who worked from three of Barajas’ sketches.

Notable Assumptions

The author assumes that Barajas would not have majorly deviated from her sketches if she made Sonora.

A
Ordinarily, Barajas’s ideas for her statues were revised substantially throughout a series of dozens of preliminary sketches.

This directly calls out a major assumption in the argument: that Barajas did not regularly deviate from her sketches. This majorly weakens the main conclusion of the argument.

B
One of the assistants who worked closely with Barajas in planning Sonora did not participate in sculpting it.

This does not impact the argument’s reasoning. The three assistants who made the statue could have also worked closely with Barajas

C
Sonora is composed partly of materials that Barajas did not frequently use in the statues that she completed during her lifetime.

It is unclear whether these materials would impact the statue's appearance. Thus, it is too weak to cast doubt on the conclusion

D
Barajas always worked from sketches when she sculpted a statue.

This does not say whether the sketches were indicative of the final version of the statue. This is too nonspecific to support

E
Barajas never took as long to complete a statue as the assistants did to sculpt Sonora.

The time it takes to create the statue does not impact how it looks, which is what the reasoning and main conclusion are focused on.


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