#19 - Must Be True

[Administrator]

Complete Question Explanation
(See the complete passage discussion here: lsat/viewtopic.php?t=10831)

The correct answer choice is (D)

This question asks for the choice that best describes the relationship between the passages. In this case, the relationship is pretty clear: the first passage describes the introduction of an invasive species as devastating, while the second just says such introduction can be a positive part of natural change.

Answer choice (A): The passages don’t take contrary stands regarding the cause of the referenced introduction of invasive species, so this choice does not describe the relationship between the passages.

Answer choice (B): This choice does not question any common assumptions, and passage B does not respond in their defense, so this choice should be ruled out of contention.

Answer choice (C): The passages do not present different evidence; rather they consider the same phenomenon but disagree regarding its ramifications.

Answer choice (D): This is the correct answer choice. As discussed, passage A warns of the dangers associated with the introduction of invasive species, while passage B claims that such introduction is not necessarily hazardous.

Answer choice (E): Passage A does not propose any particular course of action, but simply asserts that the introduction of invasive species is dangerous, and passage B does not raise questions about the advisability of a particular approach, so this choice fails on both counts and cannot provide an accurate description of the relationship between the passages.

[mandrewg]

RE: Answer choice (C): The passages do not present different evidence; rather they consider the same phenomenon but disagree regarding its ramifications.

(C) Passage A presents evidence that a particular phenomenon is widely considered to be undesirable, while passage B presents evidence that the same phenomenon is usually considered to be beneficial.

I ended up choosing D as the right answer but was debating between these two and wanted to work out why C was wrong a little more...

Even in the wording of the Passage Discussion for the section explanation, Powerscore mentions that passage B was indicating the invasive species as "beneficial", so that's why I want to just double check, as that the word "beneficial" shows up in this answer choice.

or is it the fact that the answer choice says "usually considered to be beneficial", when Passage B doesn't at all imply that [folks are trying to peg invasive species take over as "beneficial" per se]

Ultimately, what do I need to be focusing on here for me to completely strike C out for consideration? Thank you!

[Adam Tyson]

Hey mandrewg, thanks for asking! I see two reasons for eliminating answer C here. First, as mentioned in our admin's explanation, neither passage offers "evidence" of either of the claims in that answer. What evidence is in passage A, for example, that invasive are widely considered to be harmful? The third sentence reads:

"Now, however, ecologists realize that when humans introduce new species into existing ecosystems, even pristine, species-rich habitats are threatened."

But does this tell us that there is widespread agreement that invasive species are harmful? How many ecologists feel this way? What about all of us non-ecologists? Without that evidence in passage A, we don't even need to consider whether there is evidence of a benefit in passage B. The answer is already wrong!

The other reason to reject it is that passage B tells us that there is "often" increased biodiversity, but that isn't enough to say "usually beneficial", and "blending in harmlessly" doesn't qualify as a benefit, just a lack of harm.

Ultimately, the best reason to reject C is that D is much, much better. A good prephrase here would be "A says invasive species are bad and B says they are not bad". D matches that perfectly, while C does not. Pick the best answer, and you won't go wrong!

I hope that helps!

[lsatprep1215]

Hi,

I picked C for this question and when I review it I also feel ans D is much better. Can I say C is incorrect because passage B actually did not present any evidence? While I was reviewing the passage, passage A provided the Florida and Australia example but passage B did not present any example at all. Passage B is mostly about the author asserting his viewpoint to explain why invasive species isn't against nature and telling us "the issue is not whether we will be surrounded by nature but rather what kind of nature we will have around us"

[Jeremy Press]

Hi lsatprep,

When answer choice C says that "passage B presents evidence that the same phenomenon is usually considered to be beneficial," we do have some evidence that at least some people consider invasive species to be beneficial. It's found in lines 38-43, where the author says, "Indeed, in both marine and terrestrial ecosystems, ecologists have found that invasions often increase biodiversity at the local level: if you add many new species and lose few or no native species, the overall species count goes up." The problem, though, with answer choice C's description of passage B is the use of the term "usually." We cannot tell from lines 38-43 whether what those specific ecologists think is "usually" what people think.

As Adam says in his post above, we also can't tell (if that were the issue we were focused on) that invasive species as a factual matter are usually beneficial.

I hope this helps!

Jeremy