Summarize Argument: Causal Explanation
Prosperity increases carbon dioxide emissions, which drive global warming. As people become wealthier, they buy more energy-consuming items like cars, leading to higher emissions. Conversely, when countries experience economic recessions—when prosperity drops—they see significant decreases in carbon dioxide levels.
Identify Conclusion
The main conclusion is the economist’s hypothesis that prosperity drives higher carbon dioxide levels, the main cause of global warming.
A
Carbon dioxide is the main cause of global warming.
This is context. It gives the background needed to understand the argument by explaining why the author is discussing carbon dioxide emissions. The main conclusion, however, is that prosperity increases carbon dioxide emissions, not that carbon dioxide causes global warming.
B
Prosperity is an important cause of increases in the release of carbon dioxide.
This accurately captures the argument's main conclusion that prosperity drives increased carbon dioxide emissions, simply rephrasing "driving force" as "important cause."
C
When incomes rise, more people spend money on energy-consuming devices.
This restates part of the argument's first premise. The fact that rising incomes lead to more spending on energy-consuming devices supports the author's conclusion by providing evidence that increased prosperity results in higher carbon dioxide emissions.
D
Countries that experienced deep economic recessions also experienced steep drops in carbon dioxide emissions.
This restates the argument's second premise. The fact that countries in recession saw steep drops in carbon emissions shows that without prosperity, emissions fall. Thus, prosperity likely causes increased carbon dioxide emissions.
E
When people spend money on energy-consuming devices, more carbon dioxide is produced as a result.
This restates part of the argument's first premise. The fact that energy-consuming devices cause increased carbon dioxide makes it more likely that prosperity, which leads people to buy more of these devices, is a driving force behind rising carbon dioxide emissions.
"Surprising" Phenomenon
Why do people who eat lots of sugar tend to have below-average levels of unmetabolized sugar in their blood, even though eating sugar increases the level of unmetabolized sugar in the blood?
Objective
The correct answer should help explain why people who eat lots of sugar have an unexpectedly low level of unmetabolized sugar in their blood. The correct answer might tell us that these people have a feature or engage in an activity that tends to decrease unmetabolized blood sugar.
A
Persons who are overweight tend to have below-average levels of unmetabolized sugar in their blood.
We don’t know whether people who eat lots of sugar are likely to be overweight. In any case, even if they were, we would still expect sugar consumption to increase their unmetabolized blood sugar.
B
Fruits, vegetables, meats, and dairy products often contain as much sugar as sweets.
The specific food source that provides sugar has no clear impact. We have no reason to think eating sugar from fruit or vegetables wouldn’t be expected to increase unmetabolized blood sugar in the blood.
C
Consuming large amounts of sugar causes the body to secrete abnormally high amounts of insulin, a sugar-metabolizing enzyme.
For people who eat lots of sugar, sugar in the blood could be metabolized at an unusually high rate. This could explain why people who eat lots of sugar have below-average unmetabolized sugar levels.
D
Consuming large amounts of sugar can lead eventually to the failure of the body to produce enough insulin, a sugar-metabolizing enzyme.
This makes the discrepancy more difficult to explain. Less of a sugar-metabolizing enzyme would lead to even higher amounts of unmetabolized sugar in the blood.
E
Sugar passes into the bloodstream before it can be metabolized.
Even if the sugar is metabolized after entering the blood, we’re still left wondering why these people have below-average unmetabolized sugar levels in the blood.
Summary
A natural history museum has several displays of wild animals that are made by drying and mounting animal skins. In some of the older displays, the skins have begun to wear out because of low humidity and the heat from the lamps. The older displays use tungsten lamps, but the newer ones use compact fluorescent lamps made for museums. These fluorescent lamps give off the same amount of light as the tungsten lamps but produce less heat.
Strongly Supported Conclusions
The tungsten lamps contribute to the deterioration of the older displays.
Some of the older displays will last longer if the tungsten lamps are replaced by the compact fluorescent lamps.
The animal skins in the newer displays will probably deteriorate more slowly than those in the older displays.
Some of the older displays will last longer if the tungsten lamps are replaced by the compact fluorescent lamps.
The animal skins in the newer displays will probably deteriorate more slowly than those in the older displays.
A
Some of the older displays will last longer if the tungsten lamps that illuminate them are replaced by compact fluorescent lamps.
This is strongly supported. The older displays are deteriorating in part because of the heat of the tungsten lamps. Because the compact fluorescent lamps produce less heat than the tungsten lamps, the older displays would last longer if the tungsten lamps are replaced.
B
The displays that are lit by many compact fluorescent lamps are more prone to deterioration than the displays that are lit by a few tungsten lamps.
This is unsupported. All we know about the compact fluorescent lamps is that they produce less heat than the tungsten lamps and are thus better for the displays. We do not know whether a display lit by many compact fluorescent lamps might be more prone to deterioration.
C
More of the displays are lit by compact fluorescent lamps than are lit by tungsten lamps.
This is unsupported. The stimulus gives us no information about how many displays are lit by each kind of lamp. We know only that “newer displays” are lit by compact fluorescent lamps and “older displays” are lit by tungsten lamps.
D
The newer displays will not be subject to deterioration because of low humidity.
This is unsupported. The stimulus tells us that low humidity contributes to deterioration, but it does not tell us whether the type of lamp affects humidity in any way. We know only that the lamps produce different amounts of heat.
E
The humidity in the museum is lower today than it was when the older displays were first put in place.
This is unsupported. We know that low humidity contributes to deterioration, but we do not know anything about the museum’s humidity levels over time.