Vitamin supplements must be taken regularly over a period of months in

VERITAS PREP OFFICIAL SOLUTION:

In any Strengthen/Weaken/Assumption question, a huge key lies in the specific language within the conclusion. Here that conclusion is very specific, that some people should skip a dose of their vitamin supplement once a week in order to avoid the side effects that you're told can arise from taking supplements daily over a long period. Pay attention to that "once per week" specificity - do the facts of the argument tell you that once per week is a sufficient break to avoid the side effects? What if, for example, skipping an entire week is sometimes necessary for the body to flush the toxins? That extra specificity in the conclusion isn't reflected anywhere in the facts, so it stands as "low hanging fruit" that you should notice is a gap in logic.

Choice (A) is therefore a necessary assumption. And if you employ the "Assumption Negation Technique" (take the opposite of an Assumption answer choice and if it's the correct answer the negated version will directly weaken the conclusion) you'll see why. The negated version is:

"The negative side effects associated with daily vitamin supplement use CANNOT be avoided by skipping one dose of that supplement per week."

And as you can see this completely undermines the recommendation. Choice (A) is correct.

Among the other choices:

(B) is not a necessary assumption, as the conclusion is merely that "some supplement users should skip a dose once a week," but it doesn't specify which users. (A parallel example might be that "some students will score 780 on the GMAT" - even if you don't specifically know which ones, that doesn't change the conclusion.)

(C) is also not necessary. Even if the opposite were true - that the side effects are benign compared to the reasons one would take supplements - that doesn't mean that some people shouldn't still take a day off to avoid the side effects (and still presumably reap the benefits of the supplements).

(D) is irrelevant: whether users know about the side effects or not doesn't change the fact that they should skip a day to avoid those side effects. (Think about sunscreen, for example: whether you know or not about sunburn, either way you should be using sunscreen if you're out in the sun all day! It's just that if you don't know, you'll learn the hard way)

And (E) does not need to be true, either. "Life-threatening" is not a necessary standard to say that someone should try to avoid a side effect. The side effects of not brushing your teeth, for example, don't necessarily put your life in jeopardy, but they're bad enough that you'd better brush your teeth.

GMATNinja
Can you please comment on this? B looks to be fine to me if I try to negate it. But A also looks ok so not sure if this question is a waste of time.
chetan2u
Will be great if you comment as well since negating B looks to destroy the conclusion.

Hi....
The conclusion is that some person who take vitamin supplements should skip....
Had it been " some person who take THESE vitamin supplements should skip..
Now here we can say that these people should be able to differentiate..

But in the original choice, by missing out on THESE, the conclusion points towards vitamin supplements in general, so in that sense the choice B is not adressing the conclusion.
Although not a very great question but A is better than B.

I received a PM requesting that I comment.

The CR above is a PLANNING ARGUMENT.
General approach for a planning argument:
PREMISE = the plan (the action to be taken).
CONCLUSION = the goal (what the plan is intended to achieve).

In the CR above:
PLAN = once a week, to skip one dose of a daily supplement.
GOAL = to avoid the harmful side effects that result from daily intake over several months.

One way to identify the assumption is to apply the NEGATION TEST.
When the correct answer is negated, the goal will NOT be achieved if the plan is implemented.

A, negated:
The negative side effects associated with daily vitamin supplement use CANNOT BE AVOIDED be avoided by skipping one dose of that supplement per week.
This negation indicates that the goal of the plan (avoiding harmful side effects) will not be achieved if the plan (skipping a dose) is implemented.
Since the negation of A invalidates the plan, A is an assumption: a statement that MUST BE TRUE for the plan to achieve its goal.



B, negated:
It is impossible for supplement users to determine which vitamin supplements will cause negative side effects.
The plan does not require that supplement users be able to identify which supplements are problematic.
Clearly, SOMEONE ELSE -- the supplement manufacturer, a government body, perhaps a medical professional -- can advise whether a given supplement will cause harmful side effects, enabling users of that supplement to implement the plan and avoid the harmful effects.
Since the negation of B does not invalidate the plan, eliminate B.

Thanks for this explanation Brunel. I thought that this option is just the restatement of the conclusion, hence it can't be the assumption.
I missed the subtle difference.

Ok, I chose B over A
The experts' are right. Next time I'll be more careful to not get carried away by the options. I'll use the negation test properly.

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