In preparation for a large-scale tree-planting project, Thomasville

Question

In preparation for a large-scale tree-planting project, Thomasville has recorded the location, species, and condition of every tree in its downtown area. The results will be compared with results of the last such tree census, taken 20 years ago. Planting trees primarily from the species that turns out to have the best record of survival will assure downtown Thomasville of an abundant tree population 20 years from now.

Which of the following, if true, most seriously undermines the claim that the tree planting proposal will assure an abundant tree population?

A. because of the the strict laws governing industrial development, environmental conditions in Thomasville are unlikely to become harsher for trees than they have been during the last 20 years.

B. Thomasville has reliable records to show which trees in existence 20 years ago were cut down to permit new construction downtown.

C. A number of trees from one of the species widespread in Thomasville 20 years ago reached the end of their natural life span in the intervening period.

D. Very few species of trees grow as well in urban conditions as in natural conditions.

E. A city with a high proportion of an any one species of the trees can have its tree Population devastated by one outbreak of a disease.

ID 00834

GMATNinja · Accepted Answer

Samakshkapoor92 , when you answer a CR question (or an RC question, for that matter), your task is to find which answer choice is correct based on the  passage ,  not  on information that is contained in the other answer choices. Essentially, you should treat each answer choice as if it exists in a vacuum with only the text of the passage, and make your decisions one by one. So let's go through the options that are giving you trouble:

Remember, we are looking for a statement that "most seriously undermines the claim that the tree planting proposal will assure an abundant tree population." The proposal relies on data from 20 years ago and current data to determine which trees will most likely survive another 20 years. Answer choice (B) introduces a wrinkle in the data, which is that some of the trees that did not survive "were cut down to permit new construction." This, on the surface, sounds like it will create a problem for the proposal.

However, the answer choice doesn't merely state that some trees were cut down due to construction. It specifies that Thomasville  has reliable records  about exactly which trees were cut down. Can the fact that Thomasville has reliable records of this data undermine the proposal? Definitely not -- having reliable records could only help fix the complication that is introduced by the answer choice. You can eliminate (B) for this reason.

The goal of the "proposal" is to "assure downtown Thomasville of an abundant tree population 20 years from now." This answer choice tells us that a number of one particular species of tree died off naturally within the past twenty years. Is this because that kind of tree generally lives less than twenty years? Or because the trees were all planted at the same time more than twenty years ago? The first option would strengthen the proposal, while the second would call the data into question. We are not given enough information to determine the reason behind this statement, and therefore its effect on the strength of the proposal.

What we  do  know is that other types of trees  have  survived for the past twenty years, and that the proposal advocates planting those trees. So, answer choice (C) does not significantly undermine the proposal and we can throw it out.

Finally, take a look at the correct answer:

The proposal advocates planting trees "primarily from  the species  that turns out to have the best record of survival." Because one species will be planted more than the others, this answer choice significantly undermines the proposal. If the tree population can be devastated by one outbreak of a disease, then it is likely that Thomasville will not have an abundance of trees in twenty years if the town adopts the proposal.

Answer (E) is correct.

I hope this helps!

Zarrolou · Answer

We have to prove that focusing " primarily from the species that turns out to have the best record of survival will   NOT   assure downtown Thomasville of an abundant tree population 20 years from now "

A. because of the the strict laws governing industrial development, environmental conditions in Thomasville are unlikely to become harsher for trees than they have been during the last 20 years. 
This supports the conclusion. If the conditions are unlikely to become harsher, then the project seems to have good chances of succeed
 B. Thomasville has reliable records to show which trees in existence 20 years ago were cut down to permit new construction downtown. 
Very good info... Does this affect in any way the proposal? No, move on
 C. A number of trees from one of the species widespread in Thomasville 20 years ago reached the end of their natural life span in the intervening period. 
Does this waken the proposal? In these kind of question the answer is likely to show us a negative effect of the proposal itself that will undermine its results, or will show us a alternate cause of an effect.
Are we able to say that the plan will be unsuccessful because a number of trees reached the end of their life in the period? No
 D. Very few species of trees grow as well in urban conditions as in natural conditions. 
Same as B, this does not affect the proposal
 E. A city with a high proportion of an any one species of the trees can have its tree Population devastated by one outbreak of a disease 
  IMO CORRECT:   if they focus on "species that turned out to have the best record" then the proportion of those species will increase and a disease can happen. 
If this happens than "Thomasville will   not   have an abundant tree population 20 years from now"

ankurgupta03 · Answer

In preparation for a large-scale tree-planting project, Thomasville has recorded the location, species, and condition of every tree in its downtown area. The results will be compared with results of the last such tree census, taken 20 years ago. Planting trees primarily from the species that turns out to have the best record of survival will assure downtown Thomasville of an abundant tree population 20 years from now.

Which of the following, if true, most seriously undermines the claim that the tree planting proposal will assure an abundant tree population?

A. because of the the strict laws governing industrial development, environmental conditions in Thomasville are unlikely to become harsher for trees than they have been during the last 20 years.
 the conditions are unlikely to become harsher assists tree plantation, hence can not be the answer 
B. Thomasville has reliable records to show which trees in existence 20 years ago were cut down to permit new construction downtown.
 Not Related 
C. A number of trees from one of the species widespread in Thomasville 20 years ago reached the end of their natural life span in the intervening period.
 Talks about trees 20 years ago, but planting them again can increase the tree population, hence cannot be the answer 
D. Very few species of trees grow as well in urban conditions as in natural conditions.
 Not related as we are not concerned about the urban conditions 
E. A city with a high proportion of an any one species of the trees can have its tree Population devastated by one outbreak of a disease.
 This seems right as if we plant a species too much, then a disease can effect the population of the trees very much

OA Please

Samakshkapoor92 · Answer

gmat1393 ,  GMATNinja ,  GMATNinjaTwo ,  broall ,  nightblade354

guys,
can one of you explain why b is not the best choice, cant wrap the fact around my head that since c clearly shows that the data collected would be wrong or incomplete.

Mo2men · Answer

Dear  GMATNinja

Can you elaborate more on the highlighted part? I do not understand how the first strengthen and the second weaken. 
Thanks

GMATNinja · Answer

We cannot tell whether choice (C) undermines the claim that the tree planting proposal will assure an abundant tree population.

We could come up with a variety of hypothetical situations consistent with choice (C), for example:

1) Maybe the trees mentioned in (C) -- those that "reached the end of their natural life span in the intervening period" -- were all relatively young when they died. And  perhaps  because a bunch of those wimpy trees died in the intervening period, that species did not have the best survival record. So it is  possible  that, given (C), Thomasville ruled out a wimpier species in favor of a more durable one. Great!

2) But maybe the trees mentioned in (C) were actually a bunch of very old, durable trees that all just happened to reach the end of their natural life spans during the intervening period. And perhaps because a bunch of those strong/durable trees died in the intervening period, Thomasville decided not to plant that species. So it is  possible  that, given (C), Thomasville ruled out what may have been the most durable tree available. Bummer!

Then again, choice (C) only refers to "a  number  of trees." Is that a  significant  number? We have no idea. Maybe (C) only affects a few outliers and wouldn't affect the data analysis or the claim one way or the other.

The bottom line is that we have no reason to believe that (C) undermines the claim. As explained in  my last post , (E) clearly undermines the claim. So, (E) is a much better choice than (C).

tkorzhan1995 · Answer

GMATNinja , can you please help to explain how you were able to come up with two possible causes for C:
a) Survival rate is low--> Therefore, tress planted 20 years ago became extinct now--> Strenghthen argument that planting trees with high survival rate will result in abundance of trees 20 years from now; (I understand this cause. I was not able to come up with the second cause before reading your post);
B) Trees were planted more than 20 years ago. Could you please explain how you were able to come up with this cause?

GMATNinja · Answer

We're looking for an option that undermines the claim in the passage. When assessing a given answer choice, just ask yourself how the new information impacts that claim.

The information in (C) could impact the argument in several different ways -- as you've pointed out, if the trees just don't live long, then (C) would strengthen the argument. However, that reasoning assumes that the trees weren't  already  very old when the previous census was completed.

If you don't make that assumption, then (C) wouldn't strengthen the argument in the same way.

Additionally, as we pointed out in  this post , (C) talks about a "number" of trees. What does that mean? The cases you mentioned again make an assumption -- this time, that the "number" of trees is significant. In reality, (C) could be talking about a relatively  small  number -- in which case, (C) really wouldn't strengthen or weaken the claim.

To accurately think through how an answer choice impacts an argument, just be aware of any assumptions you're making. You want to assess the information on the page without relying on additional assumptions.

Because (C) could impact the argument in different ways, we can't say that it undermines the argument.

I hope that helps!

aletheia225 · Answer

This question turns on the word 'assure'. Always read carefully.

tasos777btj · Answer

How I approached this one:

Okay, so basically, we are given a project in which we are trying to find flaws in why this plan might not meet its goal: abundant tree population.

A. because of the the strict laws governing industrial development, environmental conditions in Thomasville are unlikely to become harsher for trees than they have been during the last 20 years.
 
Well, if environmental conditions are unlikely to become harsher, that is a good thing for the proposed plan and would increase the likelihood that the plan, an abundant tree population, will work.

B. Thomasville has reliable records to show which trees in existence 20 years ago were cut down to permit new construction downtown.

This basically tells us that all data collected are accurate and reliable. This, again, is a good thing for the proposed plan.

C. A number of trees from one of the species widespread in Thomasville 20 years ago reached the end of their natural life span in the intervening period.

Even if a number of trees from one of the species did something, what about all other trees? Maybe the rest of the trees did not reach the end of their natural life span in the intervening period. Here, we are given information only about the number of trees from one species. There is no way we can infer what is the case for other trees.

D. Very few species of trees grow as well in urban as in natural conditions.

This might be true, but there still could be *some* species that grow well in urban and natural conditions; therefore, if we selected those species that grow well in both environments and have a good survival record, the plan could still work.

E. A city with a high proportion of an any one species of the trees can have its tree Population devastated by one outbreak of a disease.

Raman109 · Answer

Understanding the argument -
What is the goal here - The goal is to ensure that downtown Thomasville will have an abundant tree population 20 years from now.
Plan or proposal - Plant the species with the best survival rate in the last 20 years.

The question is to weaken the claim that the tree planting proposal will assure an abundant tree population. How do we do that? Identifying the problem with the plan or problem during the implementation phase or between the plan and the goal. Option E very well highlights the problem with the plan.

Option Elimination -

A. because of the the strict laws governing industrial development, environmental conditions in Thomasville are unlikely to become harsher for trees than they have been during the last 20 years.

B. Thomasville has reliable records to show which trees in existence 20 years ago were cut down to permit new construction downtown. - If they have reliable records, it'll help them choose the right species. In a way, it goes in the direction of strengthening the plan.

C. A number of trees from one of the species widespread in Thomasville 20 years ago reached the end of their natural life span in the intervening period. - "A number of" can be say 5 trees (1%) or 400 (majority). Moreover, we don't know when those trees were planted. It may or may weaken. Distortion.

D. Very few species of trees grow as well in urban conditions as in natural conditions. - Comparison with natural conditions is out of scope.

E. A city with a high proportion of an any one species of the trees can have its tree Population devastated by one outbreak of a disease. - ok

sachi-in · Answer

The solution to unravel the RC question is to think about what the question framer is actually asking:

Prethinking:  
 The question framer is asking for a reasoning the undermines the plan that planting the currently most thriving tree will assure the abundant tree population 20 years from now.

Question to ask: What works now will it work in 20+ years ? Isn't having a diverse population more resilient ?

A. Does says it won't be harsher / same conditions will prevails ( doesn't ask the question we want )
B. Questions the census ( irrelevant )
C. Questions the census ( irrelevant )
D. All Trees not suited to Urban settings ( doesn't ask the question we want )
E. A sudden disease can wipe out the entire species of trees if there is no variation - attacks the reasoning that planting more trees of a kind is good

Engineer1 · Answer

Hi  KarishmaB   GMATGuruNY    MartyMurray , could you please provide feedback on my reasoning? Thank you!

In preparation for a large-scale tree-planting project, Thomasville has recorded the location, species, and condition of every tree in its downtown area. The results will be compared with results of the last such tree census, taken 20 years ago. Planting trees primarily from the species that turns out to have the best record of survival will assure downtown Thomasville of an abundant tree population 20 years from now.

Which of the following, if true, most seriously undermines the claim that the tree planting proposal will assure an abundant tree population?

A. because of the the strict laws governing industrial development, environmental conditions in Thomasville are unlikely to become harsher for trees than they have been during the last 20 years.

B. Thomasville has reliable records to show which trees in existence 20 years ago were cut down to permit new construction downtown.   Irrelevant

C. A number of trees from one of the species widespread in Thomasville 20 years ago reached the end of their natural life span in the intervening period.
  This looks like a good answer choice to me. The only reason it is wrong is because of the fact that one of the species reached the end of lifecycle before 20 years (intervening perdiod). Moreover, if that species did not survive for 20 years, they probably   won't be even be available to be planted   (due to end of their life span). To me,   the purple colored fact makes   this answer choice irrelevant.

D. Very few species of trees grow as well in urban conditions as in natural conditions.   Irrelevant

E. A city with a high proportion of an any one species of the trees can have its tree Population devastated by one outbreak of a disease.   This is a reason that will be a blow to the projection / plan. Hence, correct.

MartyMurray · Answer

Makes sense.
 
This could be a strengthener since it serves to eliminate the possibility that they will misjudge which trees have the best record of survival by failing to account for the fact that some were cut down to permit new construction.
 
This choice has no clear effect on the argument. It basically means that some trees from one species died. OK, great. But how many is some? Three? Ten? We'd expect some trees from a species to die over a 20-year period even if most survived. So, this choice doesn't really tell us anything that makes a difference.

On another note, what you said about the trees of the species mentioned by this choice not being available to be planted doesn't apply. The passage does not say that the plan is to replant trees currently existing in the city. Given what the passage says, we can presume that the plan is to plant NEW trees primarily from the species that turns out to have the best record of survival.
 
Yes, an irrelevant comparison.
 
Yes, exactly.

Overall, your reasoning makes sense. You just need to be a bit more careful not to create an unsupported story as you did with (C).

agrasan · Answer

Hi experts  KarishmaB   GMATNinja   IanStewart   MartyMurray

I re-attempted the question and have a following reasoning to eliminate C.

If we look at the argument, it says "Planting trees...to have the best record of survival...downtown Thomasville of an abundant tree population 20 years from now."

Option C = "A number of trees from one of the species widespread in Thomasville 20 years ago reached the end of their natural life span in the intervening period."

Best record of "survival" itself means plants that were planted 20 yrs ago and are surviving till now so what option C says doesn't matter to us because it is already known/expected from the argument that some plants won't survive and may die in the intervening period, thus, option C doesn't provide us with valuable info to affect our confidence in the conclusion.

Please let me know if you agree with my reasoning or there is a mistake.

VerbalBot · Answer

Automated notice from GMAT Club VerbalBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.

In preparation for a large-scale tree-planting project, Thomasville

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Critical Reasoning (CR) Questions

In preparation for a large-scale tree-planting project, Thomasville

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards