In most of this forest, the expected outbreak of tree-eating tussock m

Question

In most of this forest, the expected outbreak of tree-eating tussock moths should not be countered. After all, the moth is beneficial where suppression of forest fires, for example, has left the forest unnaturally crowded with immature trees, and _ _ _

The conclusion of the argument is most strongly supported if which one of the following completes the passage?

(A) more than half of the forest is unnaturally crowded with immature trees

(B) mature trees are usually the first to be eaten by tussock moths

(C) usually, a higher proportion of mature trees than of immature ones are destroyed in forest fires

(D) the expected outbreak of tussock moths will almost certainly occur if no attempt is made to counter it

(E) there are no completely effective countermeasures against the moth

LSAT

nightblade354 · Accepted Answer

In most of this forest, the expected outbreak of tree-eating tussock moths should not be countered. After all, the moth is beneficial where suppression of forest fires, for example, has left the forest unnaturally crowded with immature trees, and _ _ _

P: The moth is beneficial where suppression of forest fires, for example, has left the forest unnaturally crowded with immature trees
P: _____________________________________
C: In most of this forest, the expected outbreak of tree-eating tussock moths should not be countered

Simply looking at the structure, we are missing a premise to support the idea that we should not prevent an outbreak. Reason one being that moths can help where there are too many immature trees. We need a reason two to help bridge the conclusion to this premise; the biggest one being that if most of the forest is covered in immature trees, then most of the forest would benefit from an outbreak of moths.

The conclusion of the argument is most strongly supported if which one of the following completes the passage?

(A) more than half of the forest is unnaturally crowded with immature trees --  Pretty good, though you can hold it and come back if you are concerned about it. If most of the forest is overcrowded, this helps support the idea that most of the area should not be contained. It is perfect for our answer. If you are still concerned, plug it into the above and see if it the support works! For those thinking "but we are never told the moths attack only young trees", this is a fair point. But the premise specifically calls out immature trees overcrowding and that the moths can help, meaning there is a net benefit. Further, for those thinking "But we don't know where in the forest the outbreak will occur". Another fair point, except that we will control, per the conclusion, the outbreak in some parts; we are giving up control in the majority where the overcrowding has happened. Could the conclusion be spelled more clearly to say "in areas where overcrowding has occurred"? Yes. But it is pretty good and you can get to the conclusion without getting lost. At this point, I am just over analyzing.

(B) mature trees are usually the first to be eaten by tussock moths --  This would weaken our argument. If the mature trees are the first to go, then we still have to many immature trees overcrowding each other AND we would have less trees because the mature ones are gone. Out.

(C) usually, a higher proportion of mature trees than of immature ones are destroyed in forest fires --  We don't care about forest fires, though. Keep your focus on the conclusion. We are told that we suppress forest fires, but we are never told that immature overcrowding causes forest fires or helps fires grow bigger; these are assumptions that the writer wants you to believe, but is something we cannot assume. If we knew these assumptions, then this answer choice would help.

(D) the expected outbreak of tussock moths will almost certainly occur if no attempt is made to counter it --  OK, but who cares? We are trying to strengthen the idea that because moth is beneficial to overcrowding, we should therefore not prevent it. This just gives a random fact that it'll happen unless we do something. But this doesn't strengthen anything. If we make this true, all it says is that we have to do less work to make the outbreak happen. But this still leaves open the idea that the outbreak could be bad.

(E) there are no completely effective countermeasures against the moth --  Similar to (D), we do not care. We just want to show a benefit of some kind and this says that we can't prevent it even if we want to. But this would technically be a good thing if we want the outbreak to occur. Either way, this plays no role in our argument.

tarunanandani · Answer

In most of this forest, the expected outbreak of tree-eating tussock moths should not be countered. After all, the moth is  beneficial where  suppression of forest fires, for example, has left the forest unnaturally crowded with immature trees, and _ _ _

The conclusion of the argument is most strongly supported if which one of the following completes the passage?

(A) more than half of the forest is unnaturally crowded with immature trees --- Correct , this provides an explanation to why outbreak of moth should not be countered.

(B) mature trees are usually the first to be eaten by tussock moths --- Incorrect , its a weakener, if anything this will increase crowding of immature trees.

(C) usually, a higher proportion of mature trees than of immature ones are destroyed in forest fires --- Incorrect , redundant, it has already been mentioned that forest fire increased crowding of immature tress.

(D) the expected outbreak of tussock moths will almost certainly occur if no attempt is made to counter it --- Incorrect , not supported by the passage.

(E) there are no completely effective countermeasures against the moth --- Incorrect , not supported.

analytica233 · Answer

Great question. 
Conclusion: In MOST OF this forest, the expected outbreak of tree-eating tussock moths SHOULD NOT be countered
Because the moth is BENEFICIAL WHERE suppression of forest fires has left the forest unnaturally crowded with immature trees
Goal: add a reason to strengthen the conclusion.

(A) more than half of the forest is unnaturally crowded with immature trees
(A) is correct because it confirms the CONDITION in which moths are beneficial: "more than half   of the forest is unnaturally crowded with immature trees". So moths are beneficial in most of the forest, then in most of the forest the expected outbreak of moths should not be countered. (A) correctly strengthens the conclusion.

namangarg07 · Answer

The argument suggests that in most of the forest, an expected outbreak of tree-eating tussock moths should not be countered. The premise provided is that the moth is beneficial where suppression of forest fires has led to an unnaturally crowded state of immature trees. The missing part of the sentence should provide a reason why the moth's presence would be beneficial in such a situation.

Let's analyze each option:

(A) more than half of the forest is unnaturally crowded with immature trees: If a majority of the forest has this condition, it strengthens the idea that the beneficial aspect of the moth (thinning crowded immature trees) would apply to a large portion of the forest, thus supporting the conclusion that the outbreak shouldn't be countered in most of it.

(B) mature trees are usually the first to be eaten by tussock moths: This would weaken the argument. If the moths primarily target mature trees, their presence would counteract the benefit of thinning immature trees and could harm the more established part of the forest.

(C) usually, a higher proportion of mature trees than of immature ones are destroyed in forest fires: This statement compares the impact of forest fires on different tree ages. While it provides context about forest fires (mentioned in the premise), it doesn't directly explain why tussock moths would be beneficial in an unnaturally crowded immature forest.

(D) the expected outbreak of tussock moths will almost certainly occur if no attempt is made to counter it: This statement addresses the likelihood of the outbreak but doesn't explain why it shouldn't be countered in the specified areas.

(E) there are no completely effective countermeasures against the moth: This might be a reason why countering the moth is impractical, but it doesn't explain why the moth would be beneficial in areas crowded with immature trees.

Option (A) directly links the condition mentioned in the premise (unnaturally crowded immature trees) to the scope of the conclusion (most of the forest). If a large portion of the forest suffers from this overgrowth of immature trees, then the moth's role in thinning them would be widely beneficial, thus supporting the decision not to counter the outbreak in most of the forest.

In most of this forest, the expected outbreak of tree-eating tussock m

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GMAT Critical Reasoning (CR) Questions

In most of this forest, the expected outbreak of tree-eating tussock m

Prep Toolkit

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