Hi Victoria,
Think about what the environmentalist tells us, which is roughly this:
Premise 1: The prairie ecosystem was destroyed in order to feed cattle.
Premises 2 and 3: Before this destruction, the prairie supported bison that amounted to approximately as much meat as today’s cattle, but without the interventions (pesticides, machinery, subsidies) apparently needed to produce cattle.
Conclusion: Thus, returning the land to its uncultivated state would make it possible to restore the biodiversity of the prairie ecosystem (presumably by stopping the practices responsible for its destruction) without a significant decrease in meat production.
In a Main Point question, you need to focus on what the author wants you to believe after reading the stimulus. I agree that answer choice (B)’s reference to cost effectiveness can be seen as related to the author’s mention of pesticides, machinery, and government subsidies in one of the premises. But focusing on a single parallel like this can be dangerous if you allow the similarity to cause you to overlook the differences between the answer choice and what the author really wants to convince you is true.
Here, the conclusion actually concerns the compatibility of restoring the prairie ecosystem (as it was before cows) and continuing to produce meat in comparable amounts (by switching to bison), so I would expect to see something about both of those two elements in the correct answer choice (as we do in answer choice (E), which tells us that the ecosystem devastation could be reversed without significantly decreasing meat production).
You are correct that the conclusion does rely on the premise that bison meat would not require pesticides, machinery, or subsidies, and thus might well be less expensive—or as (B) says, more cost effective—than cattle meat. But although cost effectiveness might be a factor contributing to the environmentalist’s argument, it is not the main point that the environmentalist wants us to take away. Furthermore, when you say that (B) seems to comprehensively cover the stimulus, you are actually overlooking the fact that (B) omits to address the part of the
conclusion that concerns restoring the biodiversity of the prairie ecosystem, and therefore doesn't effectively describe the argument's main point.
Not only does answer choice (B) fail to comprehensively capture the environmentalist’s conclusion, but there are some other ways in which it departs from the stimulus that it would be helpful to notice. To address your second question, in order for (B) to be drawing a possible inference from the environmentalist’s argument, it would have to be stating something that is proven true by the argument. But take a look at (B) word for word, in comparison to what we know to be true from the stimulus:
- "(B) Protecting the habitat of wild animals so that we can utilize these animals as a food source is more cost effective than raising domesticated animals."
(B) talks about "
protecting" habitat, whereas the stimulus is about the very different process of reinstating a habitat already changed.
(B) very broadly mentions
wild animals and
domesticated animals in general, whereas the stimulus discusses only wild bison and domesticated cows.
(B) reasons that the habitat would be protected in order to
("so that we can") utilize the wild animals as food, whereas the stimulus concerns reinstating the habitat in order to restore the biodiversity of the prairie ecosystem.
(B) introduces a comparison that the stimulus never makes when (B) says that using wild animals as food is
more cost effective than raising domesticated animals.
Because of all of these departures from the environmentalist’s actual argument, (B) is not a statement proven true by the facts of the stimulus, and thus cannot be considered a valid inference.
I hope this makes more sense of this question!
Laura
