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#72957
Complete Question Explanation

Parallel Reasoning. The correct answer choice is (A).

Parallel reasoning questions commonly appear late in LR sections, around questions 17-21, and look intimidating at first glance due to how much reading they can involve. Students are often tempted to skip them due to fear about how much time they may take to solve, especially given that most students will be feeling the pressure of the clock ticking down the last few minutes by the time they get here. But these questions are usually fairly low difficulty, and may not take as much time to get through as they first appear, as some answer choices can be rejected only partway through reading them, and this is no exception.

Because the stimulus is conditional and involves multiple claims, it is wise to diagram. This also provides the Abstract Structure of the argument, which is a great way to test answer choices. The diagram here would look like this:

Premises: TDBF (temp dropped below freezing last week) :arrow: IGD (impatiens in garden would have died) :arrow: B impatiens would not have bloomed)

Premise: B

Conclusion: TDBF

Thus we have a fairly straightforward chain of three conditions, a claim that the last condition in the chain did not occur, and, via the contrapositive, a claim that the first condition in the chain did not occur. That is what we will look to match in the answers. (Especially crafty students might have noticed a subtle flaw here - what if the temp dropped below freezing last week while the author was NOT away? Maybe she would have done something to prevent them from dying? Don't get too hung up on that, and don't worry if you missed it, but it could perhaps be used to decide a tie between two answers, one of which has a similar flaw and the other being completely valid and thus incorrect.)

Answer choice (A): This is the correct answer choice. This answer diagrams out the same way:

Highly Adaptable :arrow: Thrive :arrow: Adverse Effect

Adverse Effect

Conclusion: Highly Adaptable.

(And if you are looking for that subtle flaw just to make it a perfect match, there is one - what if this species will have an adverse effect in the future, but it just hasn't happened yet?)

Answer choice (B): The conclusion here is a conditional statement, which does not match the conclusion in the stimulus. Also, this answer goes wrong three words into the second sentence, because it changes the term "adaptable" from the first conditional claim to the term "adapt." An aggressive attack on the answers might allow some students to stop reading this answer at this point, saving time and effort.

Answer choice (C): The first sentence in this answer establishes a nested conditional claim unlike anything in the stimulus (if X is true, Y is true, but only if Z is also true), and again the aggressive student would be rewarded by rejecting this answer only halfway through reading it. Those that continue to read it will also see that the conclusion is also conditional ("therefore, if"), the same problem we saw in answer B. The conclusion in the stimulus was absolute (therefore, X is true), not conditional, and so this answer is a loser for multiple reasons.

Answer choice (D): The presence of "should" in the first sentence (an opinion, rather than a fact, where our argument dealt only in facts) might lead some students to rightfully reject this answer quickly. Those that keep reading just in case will also find that there is no conditional chain of three things, just two conditions and a restatement form (a claim that the sufficient condition is present and therefore the necessary condition must also be present) instead of a contrapositive.

Answer choice (E): Again, "should" in the first sentence might be enough for some students to kill this answer quickly, but if you are looking for more assurance you will find that at the beginning of the second sentence, where they author changes the phrase "should not be introduced" to a different term of "is introduced," such that there is no connecting the first two conditional claims and forming a chain. Still not certain this is a loser? Then you should be convinced by the presence of "likely" in the conclusion, which falls short of the certainty in the stimulus ("did not").

Do not skip Parallel Reasoning questions! Attack them aggressively, with a diagram whenever they contain conditional reasoning, and be ready to jettison answers that go wrong partway through. You will find that they are mostly easy and also faster to solve than they may at first appear!
 deck1134
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#49894
Hi Powerscore,

I did this question and was a little confused. My diagramming was

The temperature dropped :arrow: impatients died :arrow: bloom

Conc: Bloom :arrow: Temp dropped

Okay, seems reasonable. Contrapositive.

(A)
Highly Adapted :arrow: Thrive :arrow: Adverse effect

Conc: adverse effect :arrow: highly adapted

Contrapositive. So this is right.

Does this seem reasonable?
 lauriesnyder
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#71078
Hi there, can you confirm that this is why B is incorrect:

Species thrive --> adaptable --> adverse affects

So... adverse affects --> adaptable

It's incorrect because it's not adverse affects --> species thrive. Right?

Thank you!
 Jeremy Press
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#71114
Hi Laurie,

Yes, that's correct!

To expand just a little, the conclusion in the stimulus relies on a contrapositive derived from a linked conditional chain, where the absence of the final necessary condition in the chain (the "third link") validates the absence of the initial sufficient condition in the chain (the "first link"). The conclusion in answer choice B relies solely on the contrapositive of the second conditional statement in the argument, not on a contrapositive derived from a linked conditional chain.

I hope this helps!

Jeremy
 ntusss
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#75581
Hi, I'm not sure if (C) could be diagrammed as below:

(first sentence)
introduced into new environment :arrow: adversely affects some species :arrow: adapt well

(Conclusion)
adapt well :arrow: adversely affect any species

Would (C) be correct if the conclusion says "adapt well :arrow: introduced into new environment"?

Thanks!
 Christen Hammock
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#75629
Hi Ntusss!

Like the complete explanation above says, answer choice (C) includes a nested conclusion. You're right that the "only if" statement adds a new necessary condition to this unusual logical chain.

Even if you changed the conclusion to "adapt well :arrow: introduced into new environment," that wouldn't solve all the parallelism problems. For example, the conclusion in (C) is conditional and not absolute ("temperatures did not drop" versus "If adapt well, then introduced").

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