Summary
Most people’s bodies make enzyme CYP2A6, which plays a crucial role in eliminating nicotine from the body. Nicotine is the addictive drug in cigarettes. Smokers whose bodies make the most common form of this enzyme tend to smoke more than smokers whose bodies make some other form of the enzyme. Why? Because the faster nicotine is eliminated from the body, the faster a person will crave another cigarette.
Strongly Supported Conclusions
The most common form of the enzyme CYP2A6 is also the form that eliminates nicotine from the body the fastest.
A
the most common form of CYP2A6 is the one that most rapidly eliminates nicotine from the body
This answer is strongly supported. Since smokers with the most common form of the enzyme smoke more due to nicotine being eliminated from the body faster, the most common form of the enzyme must cause the rapid elimination of nicotine.
B
most people whose bodies make the rarest form of CYP2A6 do not smoke at all
This answer is unsupported. We don’t know what happens in people with the rarest form of CYP2A6.
C
if one’s body does not make CYP2A6, nicotine will still be eliminated, although very slowly
This answer is unsupported. We don’t know what occurs in people whose bodies do not produce the CYP2A6 enzyme.
D
the greater the quantity of CYP2A6 that one’s body makes, the faster nicotine will be eliminated
This answer is unsupported. We don’t know if there’s a proportional relationship between the quantity of the enzyme and nicotine being eliminated from the body.
E
helping to eliminate nicotine is not the only function that CYP2A6 serves
This answer is unsupported. We don’t know if there are any other functions the enzyme serves.
Summary
Any time a bird flies, powerful forces converge on its shoulder joints. If they are flying, the bird’s wings must be kept stable during flight. If their wings are stable, something needs to balance these powerful forces. The only structure in birds that can balance these forces is a ligament that connects the wings to the shoulder joint. So that ligament must be (the correct answer is the conclusion).
Strongly Supported Conclusions
The ligament is how birds stabilize their wings while flying.
Bird Flying -> wings stable -> balance powerful forces
Bird Flying -> wings stable -> balance powerful forces
A
the only structure that is indispensable to bird flight
The stimulus gives no indication that this ligament is the *only* structure necessary for bird flight. This is too strong to support and does not follow logically from the argument.
B
the reason that a bird’s wings must be kept stable during flight
The stimulus does not explain exactly *why* the bird’s wings must be kept stable. The stimulus is primarily concerned with the importance of stability, but not the reasons for it.
C
the sole connection between the wing and the shoulder joint
The stimulus says that the ligament is the only structure *capable of balancing* the wings, not that it is the sole connection. This is too strong to support.
D
the source of the powerful forces that converge on the shoulder joint
The stimulus does not explain where these powerful forces come from. The stimulus only says that these ligaments *balance* the powerful sources.
E
the means by which a bird stabilizes its wings during flight
The stimulus says that *the only structure* capable of balancing the wings is this ligament. Thus, the ligament must keep its wings stable because nothing else can.
Summarize Argument: Counter-Position
The author proposes a different explanation for the origin of the ancient tracks on Malta. Some researchers think the tracks were intentionally cut to make it easier for carts to use them. The researchers’ evidence is that the track depth is all the same. The author acknowledges that the track depth is all the same, but thinks this just indicates the wheel diameter, which eroded the tracks to the same depth. The author’s theory that the uniform track depth indicates wheel diameter is used to support the idea that the network of tracks results from erosion from use by carts.
Identify Conclusion
The conclusion is the author’s explanation for the origin of the tracks: “The extensive network of ancient tracks on the island of Malta was most likely created through erosion caused by the passage of wheeled vehicles.”
A
The extensive network of ancient tracks on the island of Malta was most likely created through erosion caused by the passage of wheeled vehicles.
This is a verbatim restatement of the conclusion.
B
Some researchers have suggested that the ancient tracks on the island of Malta were in fact manually cut to facilitate the passage of carts.
This is the researchers’ view, which the author believes is likely wrong.
C
Some researchers cite the uniformity of the depth of the ancient tracks on the island of Malta to support the suggestion that they were manually cut.
This describes the support used by the researchers. The author reaches a different conclusion based on a different interpretation of that support.
D
The uniformity of depth of the ancient tracks on the island of Malta is probably indicative of the wheel diameter of the carts that passed over them.
This is an intermediate conclusion supported by the part after the colon. The author uses the theory that uniform track depth shows wheel diameter to help support the broader explanation that the tracks are caused by erosion from use by the carts.
E
The ancient tracks on the island of Malta were utilized until they eroded to a depth that made vehicle passage impossible.
This is a premise. It supports the intermediate conclusion that the uniform track depth shows wheel diameter. The theory that uniform track depth shows wheel diameter is used to support the broader explanation in the first sentence.