Scientists have determined that an effective way to lower cholesterol

Study split people with same cholesterol level into two groups: First who ate 3 servings of whole grains, the second did not.
After 6 months, the cholesterol levels of the first group were much lower than those of the second group.

Conclusion: Eating whole grains can have an appreciable effect on cholesterol levels.

To figure out whether it was the whole grains that led to lowering of cholesterol, we need to figure out whether the two groups differed in any other significant aspect e.g. were they following the same exercise regime? were they following the same diet (other than 3 servings of whole grain)? were they taking/not taking the same medicines? etc

Which of the following will be useful to evaluate?

a) Is it realistic to expect people to eat three servings of whole grains per day?

Irrelevant question. First group did eat 3 servings per day.

b) Were the two groups of people in the study involved in the same exercise program?

One of our relevant questions. Did they follow the same exercise program? Say first group exercised for 1 hour 4 days a week while second group exercised for 15 mins everyday. Perhaps the exercise regime of first group was responsible for lowering cholesterol. Answer to this question will be useful to evaluate the conclusion.

c) Can the same drop in cholesterol be achieved through medication?

This question is different from the question above. Had the question been: Were the 2 group following the same medicine regimen?
then it would be relevant. It would tell us a major relevant difference between the two groups.
But as given, if we say "Yes, the same drop can be achieved through medication"
or "No, the same drop cannot be achieved through medication"
Does either impact our conclusion - that the drop was due to 3 servings of whole grains? No.
Even if medicine can give the same drop, it doesn't mean that 3 servings of whole grains cannot. What else can lead to lower cholesterol is irrelevant to us. Whether whole grains led to lower cholesterol or not is out question.

d) Did the study continue to track the subjects beyond six months?

Our study period was 6 months. Whether the study tracked them beyond that is irrelevant.

e) Are most consumers aware of the different between whole grains and processed grains?

"Most consumers" are irrelevant. We know that our subjects of first group ate 3 servings of whole grains and of second group did not.

Answer (B)

OFFICIAL EXPLANATION

The correct answer is B.

The conclusion of the argument is that "eating whole grains can have an appreciable effect on cholesterol levels." This assertion is based on the fact that some people who ate three servings of whole grains every day for six months had lower cholesterol than did people who did not, even though their cholesterol levels were the same before the study began. The argument does not take into account, however, other factors, such as exercise, that may have contributed to the difference in cholesterol levels. Choice B asks whether there is indeed another factor – exercise – that should be taken into account.
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Good explanation of the correct answer above--I wanted to point out one more thing about this question type. This "which of the following...would be most useful in evaluating the claim"-question is, as victorxman analyzed, an assumption question in disguise. Recognizing categories of assumptions can be one huge tool in your kit that helps you quickly eliminate answers that are out of scope, as well as zero in on the correct one.

The red flag in this situation is that the scientists NOTICED something happened at the same time, and then they drew a conclusion about CAUSALITY. It's our classic high school dilemma-- "correlation does not prove causation!" As soon as we recognize there is a causal assumption being, made, we can quickly eliminate anything not related to the causal relationship as specifically stated in the conclusion, and label it with that handy phrase, "out of scope." This assumption type will appear again and again on the gmat.

Conclusion:
eating whole grains can have an appreciable effect on cholesterol levels
Premises:
Scientists: Eating 3 servings of whole grain a day causes decrease in colesterol levels
Study: two grups with same initial colesterol levels. People who ate whole grains had less colesterol after 6 months than people who didin't
Assumption:
All other factors remained the same between the two groups during the study or no other factor caused the result

A) Out of scope
B) This choice questions the assumption by considering an alternative factor that could have affected the results of the study and invalidate the conclusion CORRECT
C)Does nothing to adress differences between the first and second group.
D)Out of scope
E)Out of scope

in option B:

if john plays in the playing eleven ,the team is going to win.
suppose you have to evaluate this argument.

NOW when you evaluating ....john...you are checking his importance...
so how can you check his importance...
one time you will make play JOHN and see whats the team performance..
and next time you will make the team play without john...ok

analogous of OPTION B is this case....you are removing john...and seeing the importance..with remaining team.
anlogous of option C: IF mr X PLays in the team then whether team will win .===>so in this case we are not judging JOHN...we are seeing the importance of MR X

pghai has already explained very well.

hope you must be clear.

hi,

whenever you are evaluating something...you are just focussed to that thing only.

for example.
if john plays in the playing eleven ,the team is going to win.
suppose you have to evaluate this argument.
so in this case you will be just concerned about JOHN s importance.
you will not consider that if somebody mr.X will affect the team in the same way or not.

same is the case here in our question:
our conclusion is:
eating whole grains can have an appreciable effect on cholesterol levels.===>in this case...eating whole grain is acting like JOHN of previous example...we have to see the importance of this only.

now in option C

c) Can the same drop in cholesterol be achieved through medication?===>HERE MEDICATION is acting like MR X of previous example...so we dont want to know about this...

hope it helps...

I agree with C, but my question is - why Exercise in option b not acting like Mr X.?

First of all, the conclusion is: “eating whole grains can have an appreciable effect on cholesterol levels”.

C: Can the same drop in cholesterol be achieved through medication?
If two groups take the same medication, and they have the same drop in cholesterol --> FINAL RESULTS are the same, we cannot determine whether whole grains help to reduce cholesterol or not.
For example:
A and B have same cholesterol levels at 10
After eating whole grains ==> A’s cholesterol reduces to 5
B did not eat whole grains ==> B’s cholesterol is still 10
BUT, after taking medication ==> Both A’s cholesterol and B’s reduce to 3. You don’t know whether whole grains helped A? but actually, whole grains did.
KEY word is “THE SAME DROP” ==> The FINAL results the same . It doesn’t matter how A and B did, the final results are the same. But "eating whole grains" is middle factor ==> Hence, C cannot help to evaluate the middle factor.

B: Were the two groups of people in the study involved in the same exercise program?.
KEY WORD “same exercise” ==> Exercise has same effects on A and B. If A and B take different exercises ==> The final results may be different
For example:
A and B have same cholesterol levels at 10
After eating whole grains ==> A’s cholesterol reduces to 5
After exercising ==> A’s cholesterol reduces 3 more
==> Total cholesterol reduction of A is 8
B did not eat whole grains ==> B’s cholesterol is still 10
After exercising ==> B’s cholesterol reduces 3
==> Total cholesterol reduction of B: 3

Clearly, B helps you evaluate the effect "reduction 5 points of whole grains".

Hope it's clear

Yes, It's like an example:

Same exercise:
A: X+2 => reduce 3
B: 2 ==> reduce only 2
==> X is the effect of whole grains ==> You can evaluate X (X=1)

Same drop
A: X + Y => reduce 5
B: Y ==> also lead to the same reduction 5
==> You cannot determine what X is

Hope it helps.

I have a question between B and C....

b) Were the two groups of people in the study involved in the same exercise program?

--- As per OE, this is Alternative consideration making this Choice Correct....

c) Can the same drop in cholesterol be achieved through medication?

---- Why can't medication also be the alternate choice to consider? If medication can drop the chlr level then this choice should also be considered?

Pls suggest...

Thanks.. Guys... I guess I missed the key word of same exercise...

a) Is it realistic to expect people to eat three servings of whole grains per day? - Wrong: Irrelevant

b) Were the two groups of people in the study involved in the same exercise program? - Correct: Alternate Reason! If there's an alternate reason for lowering cholesterol, then it weakens the argument. If no alternate reason, the argument is strengthened.

c) Can the same drop in cholesterol be achieved through medication? - Wrong: Irrelevant

d) Did the study continue to track the subjects beyond six months? - Wrong: Irrelevant

e) Are most consumers aware of the different between whole grains and processed grains? - Wrong: Irrelevant

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