Summarize Argument: Counter-Position
The author refutes a claim made previously by some ecologists: The author argues that it is a mistake to think that natural selection will eventually result in organisms that are perfectly adapted to their environments. This is because perfect adaptation is impossible. It is impossible because environments vary a great deal, and no single set of characteristics could cause an organism to be adapted to all the conditions it might face.
Identify Conclusion
The conclusion is the author’s refutation of a once held claim: “It is a mistake to think, as ecologists once did, that natural selection will eventually result in organisms that will be perfectly adapted to their environments.”
A
It is not possible for an individual to be perfectly adapted to its environment.
This is a sub-conclusion, not the ultimate conclusion. The fact that perfect adaptation is impossible supports that natural selection will never result in perfect adaptation.
B
Natural selection will never result in individuals that will be perfectly adapted to their environments.
This accurately rephrases the conclusion. The author says it is a mistake to think that natural selection will ever result in perfect adaptation, which means natural selection will never result in perfect adaptation.
C
No single set of attributes could enable an individual organism to cope with all of the conditions that it might face.
This is a premise that supports the sub-conclusion that perfect adaptation is impossible.
D
Because an individual’s environment can vary tremendously, no individual can be perfectly adapted to its environment.
This encapsulates the sub-conclusion and its support. Both ultimately support the argument that natural selection will never result in perfect adaptation.
E
Ecologists once believed that natural selection would eventually result in individuals that will be perfectly adapted to their environments.
This is the position provided in the context that the argument refutes.
Summarize Argument: Counter-Position
The author concludes that trade routes between China and the West may have opened earlier than 200 B.C. To support this claim, the author highlights the benefits of the Silk Road as a trade route: level terrain, easily traversable mountain passes, and desert oases. The author claims that in addition to facilitating trade, these benefits would have also facilitated immigration from Africa and the Middle East to China. Since this migration began at least one million years ago, it is possible that the Silk road had opened earlier than 200 B.C.
Identify Argument Part
The claim in the question stem provides support for the possibility that the trade routes had opened before 200 B.C.
A
It is cited as conclusive evidence for the claim that trade links between China and the Middle East were established long before 200 B.C.
The author does not make a conclusive claim that the trade links were opened long before 200 B.C.; the author only claims that this was possible.
B
It is an intermediate conclusion made plausible by the description of the terrain along which the migration supposedly took place.
The claim in the question stem is not an intermediate conclusion; it is a premise that we accept at face value. The claim in the question stem does not gain support from any other part of the argument.
C
It is offered as evidence in support of the claim that trade routes between China and the West could easily have been established much earlier than is currently believed.
The claim in the question stem provides a reason to believe that trade routes could have opened earlier than 200 B.C.; it is a premise that supports the conclusion.
D
It is offered as evidence against the claim that trade routes between China and Africa preceded those eventually established between China and the Middle East.
There is no claim in the argument that trade routes between China and Africa preceded trade routes between China and the Middle East.
E
It is the main conclusion that the argument attempts to establish about intercourse between China and the West.
The main conclusion is the first sentence of the argument; the claim in the question stem is not the main conclusion.