Inorganic pesticides remain active on the surfaces of fruits and vegetables for several days after spraying, while organic pesticides dissipate within a few hours after application, leaving the surface of the sprayed produce free of pesticide residue. Therefore, when purchasing from a farm that uses inorganic pesticides, one must be careful to wash the produce thoroughly before eating it to prevent the ingestion of toxins. But one need not worry about ingesting pesticides when purchasing from farms that use only organic pesticides.

The argument above assumes that
Consumers are aware of the origins of the produce they purchase.
Produce from farms that use organic pesticides reaches the consumer within hours after it is picked or harvested.
No farm uses both organic and inorganic pesticides.
No pesticide is capable of penetrating the skin of a fruit or vegetable.
The use of either type of pesticide does not increase the cost of produce.


I chose option A, confused with the official answer, i thought the conclusion is "when purchasing from a farm that uses inorganic pesticides....But one need not worry....when purchasing from farms ....", so the argument assumes the consumer does know the origin of the farm.

Is there any other way to interpret this question?

I'll go with C.

I think A is out of scope since it does not mention anything about pesticide organic or inorganic.

OA?

The correct answer is D.

The conclusion is "one need not worry about ingesting pesticides when purchasing from farms that use only organic pesticides." (emphasis added)

Arun, that is why (A) isn't a necessary assumption: the conclusion is already limited to produce from farms that use organic pesticides. Assumptions are always unstated, but (A) is stated in other words in the argument already.

Adi, similar reason why (C) isn't necessary: since the conclusion is limited to farms that use organic pesticides, we are not concerned with farms that use both types.

_________________
Emily Sledge
Instructor
ManhattanGMAT

Emily - HOW did you know that conclusion was only regarding the "organic pesticides"? It would appear that the conclusion was what Arun pointed out? Not sure how you restrict the conclusion only to "organic pesticides".

the conclusion indicator helps one to find it here the below part is the conclusion.
Therefore, when purchasing from a farm that uses inorganic pesticides, one must be careful to wash the produce thoroughly before eating it to prevent the ingestion of toxins. But one need not worry about ingesting pesticides when purchasing from farms that use only organic pesticides.
here the author is stating that washing the produces purchased from a farm that uses inorganic pesticides will prevent the ingestion of toxins
but for those purchased from farms that use only organic pesticides one has to be careful.
here its crystal clear that the purchaser knows from which farm he is purchasing....so it can't be an assumption
D is clear cut assumption

I understood Emily to speak to just the part of the conclusion that turned out to be relevant, but I invite correction.

The most generous interpretation of Arun's account would look something like this:

PREMISE 1: "inorganic pesticides remain active on the surfaces of fruits and vegetables for several days after spraying"

PREMISE 2: "organic pesticides dissipate within a few hours after application, leaving the surface of the sprayed produce free of pesticide residue"

CONCLUSION: "(1)when purchasing from a farm that uses inorganic pesticides, one must be careful to wash the produce thoroughly before eating it to prevent the ingestion of toxins BUT (2) one need not worry about ingesting pesticides when purchasing from farms that use only organic pesticides"

Notice that on this account premise 1 supports the first part of the conclusion and premise 2 supports the second part.

This might look something like this in very schematic form:

purch. from I farm-->wash BUT purch. from O farm-->no pest. danger

inorg. pest. stay for days

org. pest. gone in hours

I would not separate this into two arguments while taking a test, but perhaps doing so will make the argument easier to follow:

purch. from I farm-->wash
inorg. pest. stay for days



AND



purch. from O farm-->no pest. danger
org. pest. gone in hours

Now, there are quite a few assumptions in these arguments: pesticides are toxic; you eat produce from inorganic farms within several days; you don't eat produce from organic farms within a few hours; produce grown on farms which don't apply inorganic pesticides are not exposed to inorganic pesticides through other means; your assumption here. There's no way we could anticipate all of them, and we shouldn't even try to on a test.

Notice that neither argument depends on A. D is an assumption of the second argument.

Even I answered 'A' , when I went through the question. I was not satisfied with the explanation given by the Manhattan , so thought I would try the forums.

But looking at the explanations here,I am still not convinced how 'D' can be the answer.

i'm afraid we can't help you further unless you indicate what you found inadequate about the explanations above and the official explanation..

_________________
Tim Sanders
Manhattan GMAT Instructor

Arun et Al,

I picked answer choice 'A' and was not convinced W/ the explanation provided.

However in retrospection I understand why 'A' is not the preferred answer choice.

My 2 cents: The question stub does mention the following

".....Therefore, when purchasing from a farm that uses inorganic pesticides...."

- So you can indeed infer that the buyser of the produce is aware of the fruits origin.


On a separate note, either there is a genre of test takers (such as myself) who over-complicate and over-think
or
this question might need to be raised to a higher score band. But I would withdraw my opinion if a MGMAT tutor / staff disagrees.

Warm regards,
Karthik

rkkarthik, good! Yes, as Emily reviewed, answer choice A is explicitly stated in the passage as part of the premise. Thus, A cannot be the assumption, since the assumption by definition is an unstated aspect of the argument. The assumption must be true for the conclusion to be logically reached.

Thank you,

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Jamie Nelson
ManhattanGMAT Instructor

Hi- Thanks a lot for your explanation and in that case considering the whole part after therefore is the conclusion, wouldn't C attack both the parts when negated, as conclusion depends on when we are buying from farms that uses organic and inorganic pesticides? Ans Choice C becomes "SOME" farm uses both organic and inorganic pesticides , then there is no way to know what type of pesticide is used "WHEN" i buy them...

you've negated C correctly, but it still doesn't matter whether we know what type of pesticide is used. the fact remains that IF the farm uses only organic pesticides you are safe (assuming the correct answer of D is also true). remember, when you negate an answer choice the argument has to fail completely for that answer choice to be correct. negating C doesn't cause the argument to fail completely..

_________________
Tim Sanders
Manhattan GMAT Instructor