A newly discovered disease is thought to be caused by a certain bacter

Question

A newly discovered disease is thought to be caused by a certain bacterium. However, recently released data notes that the bacterium thrives(prosper) in the presence of a certain virus, implying that it is actually the virus that causes the new disease.

Which of the following pieces of evidence would most support the data’s implication?

(A) In the absence of the virus, the disease has been observed to follow infection by the bacterium.

(B) The virus has been shown to aid the growth of bacterium, a process which often leads to the onset of the disease.

(C) The virus alone has been observed in many cases of the disease.

(D) In cases where the disease does not develop, infection by the bacterium is usually preceded by infection by the virus.

(E) Onset of the disease usually follows infection by both the virus and the bacterium.

KarishmaB · Accepted Answer

Let's focus on the question first because that is all that is relevant to us. (In fact, it helps to read the question first so that you can read the argument with the question in perspective)
Which of the following pieces of evidence would most support the data’s implication?

Now, before we move on, what is data's implication?
implying that  it is actually the virus that causes the new disease.

Now you have to pick an answer choice which best supports 'it is actually the virus that causes the disease'. Focus on that.

Option (C) clearly states that the virus alone has been found in many cases. Then it must be the virus that causes the disease.
It does not conflict with the premise above - 'A newly discovered disease is thought to be caused by a certain bacterium.' The premise does not say that it is caused by the bacterium. It only says that it is thought to be caused by the bacterium.

Option (B) doesn't strengthen that it is actually the virus that causes the disease. It says that the virus aids the growth of bacterium and this growth leads to development of the disease. The cause of the disease is still the bacterium. That is, if the bacterium weren't present, the virus probably couldn't do anything alone. (Note the probably here. This statement doesn't say that the virus alone cannot do anything but it also doesn't say that the virus alone can cause the disease) But we want to strengthen that it is actually the virus which is the cause.

ChrisLele · Answer

This is a tricky question - it is LSAT after all.

Let's take a look at (B). It says that the virus causes the bacteria to grow, a process followed by the onset of the disease. So this is not a simple cae of A causes B. Instead A (the virus) causes B (the bacteria) and then C (the disease) is observed.

We want an answer choice in which only A (the virus) appears with B (the disease).

(C) states that the virus alone has been observed by the disease. Without the presence of the bacterium confounding the causal chain, (C) provides the strongest support that the virus causes the disease.

Hope that helps

Abhishek009 · Answer

Based on the highlighted portion and after massive elimination process I go for (C).

sowragu · Answer

A newly discovered disease is thought to be caused by a certain bacterium. However, recently released data notes that the bacterium thrives(prosper) in the presence of a certain virus, implying that it is actually the virus that causes the new disease.

Which of the following pieces of evidence would most support the data’s implication?

(A) In the absence of the virus, the disease has been observed to follow infection by the bacterium.

(B) The virus has been shown to aid the growth of bacterium, a process which often leads to the onset of the disease.

(C) The virus alone has been observed in many cases of the disease.

(D) In cases where the disease does not develop, infection by the bacterium is usually preceded by infection by the virus.

(E) Onset of the disease usually follows infection by both the virus and the bacterium.

Show Answer

Official Answer

C

rohitt911 · Answer

Hi, the data's implication is indeed "it's the virus that CAUSES the new disease", but no where in option C it mentions that virus is the CAUSE, it just mentions that the virus has been found in many cases.

I rejected the option on these grounds, do tell me where I went wrong.

Regards
RT

KarishmaB · Answer

Option (C) SUPPORTS (improves the probability) the data's implication. You do not require to prove that data's implication is true beyond doubt. All you need to do is support it. Hence (C) is correct. If you did reject it on the grounds you mentioned, which option did you select?

rohitt911 · Answer

Option (C) SUPPORTS (improves the probability) the data's implication. You do not require to prove that data's implication is true beyond doubt. All you need to do is support it. Hence (C) is correct. If you did reject it on the grounds you mentioned, which option did you select?

I marked B, because i thought it says the GROWTH of bacterium causes the disease and not only the bacterium. And the growth of bacterium is because of the virus, hence the virus causes the disease.

KarishmaB · Answer

What is data's implication?
 It is actually the virus that causes the new disease.

Now you have to pick an answer choice which best supports 'it is actually the virus that causes the disease'. Focus on that.

Option (B) doesn't strengthen that it is actually the virus that causes the disease. It says that the virus aids the growth of bacterium and this growth leads to development of the disease. The cause of the disease is still the bacterium. That is, if the bacterium weren't present, the virus probably couldn't do anything alone. (Note the probably here. This statement doesn't say that the virus alone cannot do anything but it also doesn't say that the virus alone can cause the disease) But we want to strengthen that it is actually the virus which is the cause.

MBAPrepCoach · Answer

The causation chain here is virus then bacteria and disease. The argument is that the virus is the root cause. Without spending a lot of time with other answers I would be going to the answer choices looking for one that is going to state that the virus is the root cause. C is the one that supports this.

Farrell Dyan Hehn, MBA
Admissions Consultant & Verbal Tutor MBAPrepCoach.com

Farrell Dyan Hehn, MBA
Admissions Consultant & Verbal Tutor MBAPrepCoach.com

ynk · Answer

Can anyone please explain the difference between options 'B' & 'C' as IMO C is actually reiterating the sentence which is already stated in the argument.

MBAPrepCoach · Answer

ynk  This is a fairly common GMAT question type I like to call test and control.

Conventional wisdom: If bacteria =>disease
New idea: If virus => bacteria => disease

The new idea is that it's the virus and not the bacteria. What would strengthen this?

Answer: Where the disease is present WITH the virus, but WITHOUT the bacteria

We have "controlled" for the bacteria variable so it has to be the virus, not the bacteria.

Does this make sense?

Rohit23 · Answer

The argument is implying that it is actually the virus that causes the new disease.
Now you have to pick an answer choice which best supports 'it is actually the virus that causes the disease'. Focus on that.
Option (C) clearly states that the virus alone has been found in many cases. Then it must be the virus that causes the disease.
It does not conflict with the premise above - 'A newly discovered disease is thought to be caused by a certain bacterium.' The premise does not say that it is caused by the bacterium. It only says that it is thought to be caused by the bacterium. 
Option (B) doesn't strengthen that it is actually the virus that causes the disease. It says that the virus aids the growth of bacterium and this growth leads to development of the disease. The cause of the disease is still the bacterium. That is, if the bacterium weren't present, the virus probably couldn't do anything alone. (Note the probably here. This statement doesn't say that the virus alone cannot do anything but it also doesn't say that the virus alone can cause the disease) But we want to strengthen that it is actually the virus which is the cause. 
A, D and E could be eliminated because these statements focuses on the infection that follows the disease. Hence, C is the answer.

NinetyFour · Answer

I chose B incorrectly. I eliminated C because I thought the data's implication was "the bacterium thrives(prosper) in the presence of a certain virus, implying that it is actually the virus that causes the new disease." This means that we need to show the link between virus -> bacteria -> disease. Could someone explain why my logic is wrong?

azhrhasan · Answer

Usual causal structure question with a twist of refuting one causal relationship and supporting the other as the passage tends to do.
Answer choice C does exactly that.

amoljain · Answer

Hello Expert

In the stated question, the logic follows - virus leads to bacteria growth (thrives), which further leads to the onset of the disease. The conclusion of the data implies that the absence of the virus will not lead to the onset of the disease, as the bacteria will not thrive in these conditions.

However, nowhere it is implemented in question stem that the virus is the actual cause of the disease. The disease is still caused by bacteria, and the virus is just aiding the bacteria to thrive in the conditions. In other words, virus is acting just as a catalyst.

In option C, virus is observed to be the reason for the disease itself, without the bacteria, which goes against the conclusion of the study.

IMO, option B is the closest to the reasoning provided.

Your views are highly appreciated.

blabla789 · Answer

I am still confused with C. If we clearly read the option, The virus alone has been observed in "many" cases of the disease. Now, "many" can be a 10k out of a 1M cases, which is eventually very subjective.

I would have easily chosen C if it were "most" instead of "many".

I would have easily chosen C if it were "most" instead of "many".

durant25 · Answer

KarishmaB

Isn't the wording between C and B a little different? In the case of B, we clearly know the disease happens (often takes place). In C, I can say that the virus is observed, but do we know if it's causing the disease? Option C does not explain that, pls help.

KarishmaB · Answer

(C) The virus alone has been observed in many cases of the disease.

This means that in many cases in which the disease happened, only the virus was observed in the individual, not the bacterium. "many cases of the disease" means the disease happened. It supports that the virus is the cause. It doesn't prove that the virus is the cause but in strengthen questions, we don't have to prove. We have to just improve the possibility and that is done by option (C).

egmat · Answer

Hi durant25,

You've spotted the real tension here, so let me build on the point ChrisLele and MBAPrepCoach made about "controlling" for the bacterium.

You're right that  B  uses the word  disease  explicitly and  C  only says the virus was  observed . But notice what B actually describes: "The virus has been shown to aid the growth of  bacterium , a process which often leads to the onset of the disease." Read the chain - virus → bacterium grows → disease. The thing sitting right next to the disease is still the  bacterium . The virus is only a helper. So B, despite naming the disease, actually keeps the bacterium as the cause - the opposite of what we want to support.

Why C works even without the word "causes":  you don't need a choice that  proves  the virus causes the disease. A strengthener only has to make "it's actually the virus"  more likely . C says "the virus  alone  has been observed in many cases of the disease" - meaning the disease showed up  with the virus and no bacterium at all . If the disease can happen without the bacterium, then the bacterium isn't necessary, and the one thing left standing is the virus. That raises the probability that the virus is the true culprit - which is exactly what "support" asks for.

So the difference isn't "which choice says the word disease." It's  which choice isolates the virus as the actor.  B never removes the bacterium; C removes it.

Turn one knob to feel it:

- If C said the virus was observed  along with the bacterium  in those cases - would it still support the virus? No, both are present, so you can't tell which one did it.
- Because C says  alone , the bacterium is ruled out, and only the virus remains.

That word "alone" is doing all the causal work - you don't need the sentence to state "causes" out loud.

Answer: C

A newly discovered disease is thought to be caused by a certain bacter

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A newly discovered disease is thought to be caused by a certain bacter

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