The answer should be D. If the molecular structure of chemicals in volcanic eruptions does not prevent those chemicals from reaching the stratosphere, those chemicals are more harmful than act of man.

If we negate this statement, "the molecular structure prevent chemicals to reach the stratosphere" the conclusion "chemicals are more harmful than act of men" falls apart.

I must say I found B very tempting but negate D and the conclusion falls apart.

IMO E..

Answer should be D.

My solution is below.

The popular view is that Ozone layer's depletion is real, as certain as Neil Armstrong's landing on the moon. While that may be the case, the attribution of such depletion to man-made chemicals is not true. Mount Pinatubo in the Philippines spewed forth more than a thousand times the amount of ozone-depleting chemicals in one volcanic eruption than all the fluorocarbons manufactured by wicked, diabolical and insensitive corporations in history. Mankind can't possibly equal the output of even one eruption from Pinatubo, much less 4 billion years' worth of them, so how can it be held responsible for destroying ozone.

Which of the following is an assumption on which the argument of the author depends?

>> So, this is an assumption question. We need to find a conclusion and gap in logic.

Conclusion: "so how can it be held responsible for destroying ozone." = humankind can't be responsible for destroying ozone

Evidence: People release less amount of the chemicals than one volcano does.

Gap: Chemicals from volcano and corporations can be different in terms of their effect on
ozone. So, small amount of human exhausted chemicals can harm more.


A. It would take mankind more than 4 billion years to destroy Ozone.
>> So, what? It does not address the conclusion who is really guilty in Ozone destruction.

B. Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons.
>> This one is tempting. But it is wrong because of key word "each".
Perhaps, there are a few unique molecules which work differently, but they can't influence conclusion.

C. The amount of ozone-depleting chemicals released during a single eruption in Mount Pinatubo is much higher than the quantity of fluorocarbons produced by the companies
>> It is just rewording initial evidence. We already know this fact.

D. The molecular structure of ozone-depleting chemicals released during a volcanic eruption does not prevent them from reaching the stratosphere, the layer of the atmosphere where the ozone layer resides.
>> This is it. If it is true than there are higher chances that volcano chemicals will endanger ozone at least equally as corporation's chemicals does.

E. The rate at which an ozone depleting chemical, whether man-made or released in a volcanic eruption, is released is not more important in the destruction of ozone layer than the quantity of chemicals released.
>> Does the rate of chemical emission address the gap? Not at all. Meanwhile, we don't know. Perhaps, ozone is able to restore itself. So, rate could be more important that overall amount.

very interesting is B.

this kind of wrong answer should be studied so that we realize it soon next time we see it.

I name it
RELEVANT BUT NOT STRONG ENOUGH TO BE CORRECT.

e gmat, do you have any tip/strategy to realize this kind of wrong answer quickly?

thank you e gmat

B is a strengthener, not assumption.

the presense of B confused us.

how to counter this bad situation? pls advise. in the test room we are nervous and maybe dose not realize the bad B.

oki my pick D . but i will elaborate on B ,which says : Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the same quantity of ozone as a molecule of fluorocarbons.
now if we negate B and say that :Each molecule of ozone depleting chemical released during an eruption of Mount Pinatubo destroys the not same quantity of ozone as a molecule of fluorocarbons.then the conclusion does not fall apart .because lets say fluorocarbons destroys 100 unit of ozone and Each molecule of ozone depleting chemical destroys ,lets say ,95 unit of ozone , in that case the conclusion stands rock solid that is humans sud not be blamed for the damage !!