Vicente: Off-road vehicles should be prohibited in our province's main wilderness park. In the past decade, the park's bird populations have declined substantially. This decline is probably attributable, at least in part, to off-road vehicle use. The number of off-road vehicles has been increasing steadily. Their use disrupts sensitive bird habitats.
In Vicente's argument, the two portions in boldface play which of the following roles?Looking at the argument, we see that the first sentence, "Off-road vehicles should be prohibited in our province's main wilderness park," is supported by everything else that follows. So, the first sentence states the main conclusion of the argument.
With that information in mind, let's go through the answer choices.
A. The first is a conclusion for which support is offered, and itself is offered to support the second; the second is the main conclusion drawn in the argument.The first part of this choice is correct since the first boldfaced portion is a conclusion for which support is offered. After all, "This decline is probably attributable, at least in part, to off-road vehicle use," is supported by the statements that follow it, "The number of off-road vehicles has been increasing steadily," and "Their use disrupts sensitive bird habitats."
However, the second and third parts of this choice are incorrect since since, as we just saw, the second boldfaced portion supports the first and thus is a premise rather than the main conclusion of the argument.
Eliminate.
B. The first is a premise offered to support the second; the second is a conclusion drawn in the argument but not the main conclusion.This choice is completely incorrect.
For one thing, it's not the case that the first boldface supports the second. Rather, "This decline is probably attributable, at least in part, to off-road vehicle use," is supported by the facts "The number of off-road vehicles has been increasing steadily," and "Their use disrupts sensitive bird habitats."
Accordingly, we can see also that the second boldface supports the first and is not supported by any other statement in the argument. Thus, the second is a premise rather than a conclusion of the argument.
Eliminate.
C. The first is a premise offered to support the only conclusion drawn in the argument; so is the second.The very beginning of this choice is correct since the first boldfaced portion does support the main conclusion of the argument.
However, this choice quickly goes wrong because the main conclusion is not "the only conclusion drawn in the argument" Rather, the first boldfaced portion is also a conclusion, an intermediate conclusion that is supported by the two sentences that follow it.
Also, the second part of this choice is incorrect because, while the second boldfaced portion is a premise, it doesn't directly support the main conclusion of the argument. Rather, it supports the first boldfaced portion.
Eliminate.
D. The first is the main conclusion drawn in the argument; the second is another conclusion for which support is offered, and itself is offered to support the first.This choice may be the trickiest choice in this question. It's easy to get the impression that the first boldfaced portion is the main conclusion of the argument if you read the argument too fast and miss the fact that the first sentence states the main conclusion, and then the second boldfaced portion can seem to be supported by the sentence between the two boldfaced portions. Thus, if we're not careful, we can decide that this choice is correct.
However, as we saw, the main conclusion of the argument is stated by the first sentence of the passage, which is supported by the first boldfaced portion.
Also, the second boldfaced portion is not a conclusion supported by anything else in the passage. Rather, it's simply a statement of fact about the use of off-road vehicles.
Eliminate.
E. The first is a conclusion drawn in the argument but not the main conclusion; the second is a premise offered to support the first.This choice matches exactly what we have seen through analysis of the argument and our review of the other choices.
The first boldfaced portion is a conclusion that is supported by the two statements that follow it, one of which is the second boldfaced portion.
Then the first boldfaced portion supports the main conclusion of the argument, which is the first statement of the passage. So, it is the case that the first boldfaced portion is not the main conclusion.
Thus, this choice accurately describes the roles of the two boldfaced portions of the passage.
The correct answer is