Lofgren's disease has been observed frequently in commercially raised

C for me.

Lofgren's disease has been observed frequently in commercially raised cattle but very rarely in chickens. Both cattle and chickens raised for meat are often fed the type of feed that transmits the virus that causes the disease. Animals infected with the virus take more than a year to develop symptoms of Lofgren's disease, however, and chickens commercially raised for meat, unlike cattle, are generally brought to market during their first year of life.
Which of the following is most strongly supported by the information provided?

C: A failure to observe Lofgren's disease in commercial chicken populations is not good evidence that chickens are immune to the virus that causes this disease.

Hi Guys,

While we are discussing the option B and C, let's revisit the question once again...the question says:

Which of the following is most strongly supported by the information provided?
...
B: There is no way to determine whether a chicken is infected with the Lofgren's disease virus before the chicken shows symptoms of the disease.
C: A failure to observe Lofgren's disease in commercial chicken populations is not good evidence that chickens are immune to the virus that causes this disease.
...
Now if we consider option C, what it signifies is that the:
conclusion of the given argument, say Y, is: Chickens are immune to the virus that causes this disease.
and it's given evidence in the argument, say X, is: A failure to observe Lofgren's disease in commercial chicken populations
And the option C then means that X does not lead to Y.

So, for option C to be true, author must provide both coclusion - Y and evidence X in argument, whereas,
- the argument never talks about the conclusion to be Y (it can be infered only), and,
- Also you cannot consider X as an evidence (not even as an assumption) because author did say that disease can be observed rarely in chicken...the author never talked about failure to observe disease.
So, even if Y is considered as inference (as trivikram pointed out), the option C cannot be considered as true, since X is never mentioned as evidence or assumption.

Using POE, the option B then wins.

Let me know if you have some other views.

Argument (for easy reference): "Lofgren's disease has been observed frequently in commercially raised cattle but very rarely in chickens. Both cattle and chickens raised for meat are often fed the type of feed that transmits the virus that causes the disease. Animals infected with the virus take more than a year to develop symptoms of Lofgren's disease, however, and chickens commercially raised for meat, unlike cattle, are generally brought to market during their first year of life.
"

I will go for C.

Here is my explanation:

Premise1: Lofgren's is rare in chickens than it is in cattle.
Premise2: Both cattle and chicken eat same food that may cause disease.
Premise3: It takes one year for symptoms to appear.
Premise4: Chickens are brought to market in their first year.

Now the question asks for inference NOT the conslusion.
What we can infer?

1. It takes 1 year for symptoms to year doesn't mean that the disease can not be detected in first year. Only thing we can infer is NO sysmtoms can appear before 1 year and if sysmtoms are there then the chicken is atleast one year old.

2. The rarity of disease is not related to food. There MUST be some other cause of rarity.

3. No symptoms of disease have been observed in chickens brought in market.

Using 2nd inference we can say that if we have not observed the disease in chickens then it doesn't mean that they are immune. Chickens are also susecptible to disease but only thing is we have not observed.

A. transmission to human beings is not covered in the stimulus, hence eliminate.
B. we don't know if any such method exists in nature, hence eliminate. (another valid reason for elimination is that this option is too extreme)
C. correct
D. we don't know if an animal not showing any symptoms of the disease can transmit it, hence eliminate
E. completely out of scope - eliminate

My reasoning is also same like you. In the passage the author didn’t mention anything about immunity. I am also standing with B in this one.


Sent from my iPhone using GMAT Club Forum mobile app

Why I believe B is wrong.

No where does it say in the passage that it is impossible to figure out whether the chicken has the disease before it shows symptoms. There may be tests they COULD run, even before the chicken shows symptoms, that would show the chicken has the disease. We just are not told anything about this.

However, since commercial chicken populations are brought to market BEFORE the symptoms show up——(symptoms show up > 1 year and the chickens are brought to market in 1 year or less)——

What C says must be True. A chicken can have the disease, be brought to market before showing any symptoms, and no one would be able to tell.

This is why a failure to observe the symptoms in commercial chickens is NOT good evidence that these chicken are immune. Maybe the chickens have the disease but it’s BEFORE the time when the symptoms start to show. After all, we are told that chickens are brought to market before any symptoms have a chance to appear.

I’ll admit it isn’t the best written passage and there are a few holes....but C is more strongly supported by the Facts.

Posted from my mobile device

Here's my two cents for eliminating choice B. Nowhere in the passage the author mentions anything about ways to determine the Lofgren's disease. It only says that it can take upto a year for symptoms to show up.

May be if we do the tests before even the symptoms appear, we can identify the disease. Again, unless we show symptoms why would anyone want to perform the tests. They would assume the chickens are healthy.

The summary is the argument does not talk about the tests used to determine Lofgren's disease. It only talks about its symptoms.

Please give kudos if you like my explanation.

Regards

Posted from my mobile device

Hi Fdambro294 ,

My thoughts on between B and C, since these two are close calls.

As you rightly mentioned, in B there can be ways to find the disease in the chicken. So it's not necessarily true.

But as far as C is concerned I agree with Vinodsai1995 there is no mention of immunity in the stimulus. So for C to be absolute correct it should mention "more immune than cows" in it IMO.

Experts, what do you think.?
VeritasKarishma AndrewN IanStewart

Thank you.

Yea, I agree with you. This is one of those questions that skates along the edge between 2 answers......I too would love to see what another expert thinks.

The stem begins by saying we see Lofgren's in cows, but not (or "rarely") in chickens. That information seems to be leading to a plausible conclusion: that Lofgren's doesn't affect chickens, or that chickens are immune to Lofgren's. But then we learn that it takes a year before Lofgren's symptoms appear, and chickens are killed before they are a year old. If that's true, even if chickens can contract Lofgren's, you'd never see it, because the chickens don't live long enough to exhibit symptoms.

That's essentially what answer C says: if commercially-raised chickens don't live for a full year, we can't conclude anything about whether Lofgren's affects chickens by observing commercially-raised chickens. Whether they can get Lofgren's or not, we'd never know by looking at them.

B is certainly wrong here - there's no information in the stem that tells us whether there are, say, medical tests that can detect Lofgren's before symptoms appear. As we're all probably acutely aware these days, people can carry viruses, they can be asymptomatic, and yet we can still test them for those viruses. It's often true that we don't need to see symptoms to test for diseases, and there's nothing in the passage that tells us one way or the other what the situation is with Lofgren's testing.

Hello, Nups1324 and Fdambro294. The language of the two answer choices in question offers insights into why one answer is overreaching and the other is not. Also, note that despite the Must be True tag, the question itself states most strongly supported. This is a difference worth considering. A must-be-true answer cannot deviate from what the passage lays out; a most-strongly-supported answer merely needs to be the most logical endpoint—among the five answer choices provided—of the information presented in the passage. With that said, how about we take a closer look, with a focus on the two answers in question?


What has been discussed above about (B) is accurate. For all we know, there could exist some sort of blood test or just about any other way for scientists or even farmers to be able to determine that a chicken was infected with Lofgren's disease. The passage provides no insight into the matter. The definitive is no way is too strong. Meanwhile, choice (C) touches on a notion that is supported by the passage, namely that chickens can be infected with the virus, since Lofgren's disease has been observed, albeit very rarely, in chickens. The passage even goes out of its way to posit why the disease may have only rarely been observed in chickens, since these animals are generally killed within their first year of life, and symptoms take more than a year to present. We can conclude, therefore, that chickens are not immune to the virus, and also that not observing symptoms of Lofgren's in chickens is not proof that the chickens do not have the disease. In other words, choice (C) is most strongly supported by the information provided, and that is all we are looking to do.

I hope that helps. Trust the exact phrasing of the question stem in approaching a CR question. Thank you for thinking to bring me into the dialogue.

- Andrew

IanStewart AndrewN

Thank you much for your timely response.

Posted from my mobile device

(B) is certainly wrong. Note the language:
"Lofgren's disease has been observed frequently in commercially raised cattle..."
It doesn't say, "cattle have frequently tested positive..." So it seems we are relying on observation i.e. noting the symptoms.
So whether there is a way to determine the disease before symptoms appear, we have no idea at all. So (B) is incorrect.

C. A failure to observe Lofgren's disease in commercial chicken populations is not good evidence that chickens are immune to the virus that causes this disease.

Note the use of the same word "observe" here. A failure to observe does not guarantee that the disease does not exist in chickens. The use of the word "immune" is acceptable because we are told that the chicken are fed the virus but do not show symptoms. The argument is trying to tell us this that just because we do not observe the disease in chicken, doesn't mean it is not there. The chicken are killed before the symptoms may appear. Not being able to observe the disease in chicken doesn't mean that it is not there in them (that they are immune). They may or may not be.

P1 - Animals infected with the virus take more than a year to develop symptoms of Lofgren's disease
P2 - Chickens commercially raised for meat, unlike cattle, are generally brought to market during their first year of life.
Conclusion - Lofgren's disease has been observed frequently in commercially raised cattle but very rarely in chickens.

Hence - C is correct. Because Chickens are brought to the market before 1 year i.e. before symptoms show up is not an indication that chickens develop it rarely.