"Surprising" Phenomenon
Why would the cholesterol of someone taking the medication be typically higher than the average cholesterol of someone in that person’s age group even though the medication is effective in lowering cholesterol?
Objective
The correct answer should tell us about a difference between people who take the medication and people who don’t that might explain why people who take the medication have higher average cholesterol despite the medication’s effectiveness. For example, maybe people who take the medication start off with above average cholesterol, which could be why the take the medication in the first place. Or maybe people who take the medication engage in cholesterol-increasing activities that the average person does not.
A
A recently developed cholesterol-lowering medication is more effective than the medication described above.
A new, different drug has no impact if we have no reason to think that the average person takes that new drug.
B
Another medication is prescribed to treat high cholesterol just as often as the medication described above is.
A different drug has no impact if we have no reason to think that the average person takes that new drug. Even if we did know that the average person takes a different drug, we don’t know that the different drug is more effective at decreasing cholesterol.
C
In most cases, people with high cholesterol levels are not treated with drug therapy but are put on restrictive low-cholesterol diets.
What happens to most people with high cholesterol doesn’t matter, because we’re trying to explain a discrepancy concerning people who are on the cholesterol-reducing drug.
D
The medication described above is usually prescribed only for people whose cholesterol level is at least 30 percent above the average for their age group.
This tells us people given the medication typically start with cholesterol significantly higher than average. That’s why the drug, even though it helps reduce cholesterol, does not bring the drug-takers’ cholesterol level down to the average person’s cholesterol level.
E
Within the population as a whole, approximately the same number of people have relatively high cholesterol levels as have relatively low cholesterol levels.
The specific number of people with high or low cholesterol does not affect average cholesterol levels of people who take the medication or average cholesterol levels of people who don’t take the medication.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that the regular sequence of ice ages Earth has experienced since 800,000 years ago are caused by Earth’s passing through clouds of cosmic dust. According to this theory, the cosmic dust enters Earth’s atmosphere, which dims the sun, causing an ice age.
Notable Assumptions
The author assumes there’s no other explanation for what causes Earth’s regular sequence of ice ages. The author assumes that the occurrence of ice ages is correlated with Earth’s passage through clouds of cosmic dust.
A
Earth did not pass through clouds of cosmic dust earlier than 800,000 years ago.
This strengthens by defending the argument from the possibility that passage through cosmic dust occcurred before the ice ages starting to occur.
B
Two large asteroids collided 800,000 years ago, producing a tremendous amount of dense cosmic dust that continues to orbit the Sun.
This helps establish that the dense cosmic dust the author’s hypothesis requires actually exists and correlates with the beginning of the ice ages.
C
Earth’s average temperature drops slightly shortly after volcanic eruptions spew large amounts of dust into Earth’s atmosphere.
This strengthens by showing that dust in Earth’s atmosphere can reduce Earth’s average temperature. This makes the author’s theory about dust causing ice ages more plausible. Although (C) is about volcanic dust, it still shows that dust in atmosphere can cool the Earth.
D
Large bits of cosmic rock periodically enter Earth’s atmosphere, raising large amounts of dust from Earth’s surface.
(D) tells us that cosmic rock periodically enters the atmosphere. But does the Earth get colder after this happens? We don’t know. Do these periodic entries of cosmic rock coincide with Earth’s ice ages? We don’t know. (D) has no impact.
E
Rare trace elements known to be prevalent in cosmic debris have been discovered in layers of sediment whose ages correspond very closely to the occurrence of ice ages.
This provides evidence of a correlation between cosmic debris and the occurrence of ice ages.