"Surprising" Phenomenon
Despite TBT being banned, the endangered oyster population hasn’t grown.
Objective
The correct answer will be a hypothesis that explains why the TBT ban didn’t help the endangered oyster population as expected. That explanation must provide some new problem facing the oyster population after TBT was banned, or some reason that TBT was in some way useful to the oyster population.
A
The increase in water temperature has slowed in the years since the legislation was passed.
The increase in water temperature wasn’t the problem. We need to know why the TBT ban didn’t help the osyters.
B
Native oysters rely on different sources of food than do the barnacles that live on the hulls of boats.
If anything, this eliminates one way the TBT ban could’ve gone wrong—that barnacles competed with oysters for food. It certainly doesn’t explain why the TBT ban was ineffective.
C
TBT also killed imported varieties of oysters that flourish at the expense of native oysters now that the waters are warmer.
TBT eliminated competition that harmed the native oysters. The competition intensified after the TBT ban, hence why the native oyster population hasn’t rebounded.
D
Other chemicals that are used to remove barnacles from the hulls of boats seem to have little effect on the oyster populations.
Like (B), this removes some possible downside of the TBT ban—that the chemicals that replaced TBT were also harmful to the oysters. We need to know why the oyster population didn’t grow after the TBT ban.
E
TBT is more deadly to oysters in colder waters than in warmer waters.
TBT was banned, so it can’t factor into an explanation for why the oyster population hasn’t rebounded.
Summarize Argument
The editorial concludes democracies should work to ensure constant economic expansion. Why? Because expansion gives people the opportunity to improve their economic standing, and economic classes that prevent people from improving their standing strengthen political divisions in democratic societies, making government worse.
Notable Assumptions
The editorial assumes a democracy is less likely to be segmented into classes if its people have better chances to improve their economic position. It also assumes that divisive political groups are less likely to stand in the way of good government if they’re weak, and that constant economic expansion wouldn’t create any new issues for good governance that outweigh its advantages.
A
Discord within a society tends to increase inequities in the distribution of wealth.
This doesn’t say eliminating discord reduces those inequities. In addition, the editorial doesn’t claim constant economic expansion will reduce the total amount of discord in a society—just that a failure to expand will cause divisive political factions to become stronger.
B
Political factions are sometimes willing to overlook their differences to back policies that are conducive to economic expansion.
This exception to the rule doesn’t disprove the rule. It doesn’t change the editorial’s premise that divisive political factions make good governance harder to achieve.
C
Economic expansion results in a proportionally greater increase in earnings for people at low income levels than for people at other income levels.
This strengthens the editorial’s assumption that improved economic mobility will make class divisions less stark. It rules out a damaging possibility: that economic expansion mostly helps higher-income people, making class divisions greater.
D
Economic expansion cannot occur unless there is significant financial investment in the economy by people at the highest income levels.
If anything, this weakens the argument. It suggests that economic growth may be self-defeating in the long run, since reducing class divisions may reduce the number of very wealthy people willing to invest.
E
The presence of divisive political factions can be an obstacle to economic expansion.
This doesn’t address the editorial’s primary assumption: that improved economic mobility decreases class divisions. It suggests that failure to expand the economy is self-reinforcing, not that it leads to bad governance.
Summarize Argument
The author concludes that the Internet will someday gain a humanlike intelligence. This is based on an analogy to the human brain. Computers that make up the Internet form an interconnected collection that transmits information, which is similar to how neurons form in the human brain. In addition, the Internet is growing at millions of points, which is similar to a developing human brain.
Identify and Describe Flaw
The author assumes that the superficial similarities between the Internet and a brain imply that the Internet will eventually gain a another similarity related to intelligence. This overlooks the possibility that there’s no connection between the existing similarities and the development of a similar intelligence.
A
equates the complexity of an entity with the intelligence of that entity
The author doesn’t assume that the more complex an entity is, the more intelligent. He notes that the Internet is similar to the brain in its complexity, but reasons that because of this similarity, another similarity will develop. This isn’t the same as equating two concepts.
B
fails to consider the possibility that other technologies may simulate human intelligence before the Internet does so
The author doesn’t say the Internet will be the first to simulate humanlike intelligence. So this possibility doesn’t undermine the argument.
C
draws a dubious analogy between the information that is processed by the human brain and the information that is transmitted on the Internet
The analogy isn’t between the info processed by a brain and the info transmitted by the Internet. It’s between a brain and the Internet. They are similar in that they both have components that transmit info (computers and neurons). But this doesn’t suggest the info is analogous.
D
fails to give an indication of why the characteristics it focuses on are sufficient for the eventual development of humanlike intelligence
The author fails to show why the features it focuses on (manner of transmitting info, growing at millions of points) would lead to the development of intelligence. Why do these superficial features establish that the Internet will become intelligent? We don’t get any reason.
E
presumes, without providing justification, that the people administering the Internet are interested in developing a system with humanlike intelligence
The argument doesn’t assume anything about people’s interest. The argument is based only on an analogy between brains and the Internet, and none of the analogous features involve the interests of people.
Summarize Argument: Phenomenon-Hypothesis
Some scientists hypothesize that the Amazon River previously flowed into the Pacific Ocean, not the Atlantic Ocean. Why? Because some freshwater fish in the Amazon are descended from saltwater fish that lived in the Pacific but not the Atlantic, and the Andes Mountains currently separate the Amazon from the Pacific.
Notable Assumptions
The scientists assume some Amazon fish are descended from Pacific Ocean fish because the Amazon used to flow into the Pacific, and not for some other reason. This means assuming ancestors of the freshwater fish entered the Amazon when it flowed into the Pacific. It also means assuming the Andes Mountains prevent any fish from traveling from the Pacific Ocean to the Amazon River on its current route.
A
In many cases, species of freshwater and saltwater fish that share certain characteristics do not in fact share a common ancestor.
Since the Amazon fish are known to have descended from the Pacific-dwelling species, this is irrelevant. It doesn’t provide any new information suggesting the Amazon was once connected to the Pacific.
B
Most of the fossilized remains of the now-extinct saltwater fish from the Pacific Ocean date to a period prior to the formation of the Andes Mountains.
This confirms that the Pacific-dwelling species lived before the Andes separated the Amazon from the Pacific. It rules out the possibility that the Pacific-dwelling fish emerged when the Amazon was already inaccessible from the Pacific because of the Andes Mountains.
C
Many species of fish that inhabit the Atlantic Ocean are related to fish species that are known to inhabit the Pacific Ocean.
If anything, this weakens the argument. It suggests an alternative hypothesis: that an intermediate descendant of the Pacific-dwelling species lived in the Atlantic, and served as an ancestor for the current freshwater species in the Amazon.
D
The Andes Mountains extend from the northernmost to the southernmost extremes of the South American continent.
This is irrelevant. It’s important only that the Andes cut off the Pacific from the Amazon—their precise geographical span doesn’t affect the argument.
E
There are very few fish species that are known to be able to survive in both fresh and salt water.
If anything, this weakens the argument. It suggests it’s unlikely that saltwater fish from the Pacific entered the Amazon directly and descended into the present-day freshwater species.