Scientists have modified feed corn genetically, increasing its resista

Hi teaserbae,

Scientists have modified feed corn genetically, increasing its resistance to insect pests. Farmers who tried out the genetically modified corn last season applied less insecticide to their corn fields and still got yields comparable to those they would have gotten with ordinary corn. Ordinary corn seed, however, costs less, and what these farmers saved on insecticide rarely exceeded their extra costs for seed. Therefore, for most feed-corn farmers, switching to genetically modified seed would be unlikely to increase profits. --> Highlighted part is the conclusion

The conclusion is related to profit. We need something to evaluate that part. This choice doesn't impact the profit at all.
A "yes" to the option will mean that there are insects that equally impact modified and normal corns. Thus, as per the premise conclusion still holds.
A "no" to the option will mean that there are insects against which both modified and normal corns are equally effective. Thus, as per the premise conclusion still holds.
In either case the conclusion still holds. Thus, A is wrong.

Hope that helps!

Understanding the passage

Scientists have modified feed corn genetically, increasing its resistance to insect pests.

• Scientists have improved feed corns' resistance to insect pests by genetically modifying it.

Farmers who tried out the genetically modified corn last season applied less insecticide to their cornfields and still got yields comparable to those they would have gotten with ordinary corn.

• Farmers who used genetically modified corn last season applied a comparatively less quantity of insecticide to their cornfields.
• Even with the use of a lower quantity of insecticide and genetically modified seeds, the yields were the same as with ordinary corn.

Ordinary corn seed, however, costs less, and what these farmers saved on insecticide rarely exceeded their extra costs for seed.

• Ordinary seeds are cheaper than genetically modified seeds.
• The money saved on insecticide is often less than the extra cost for genetically modified seeds.

Therefore, for most feed-corn farmers, switching to genetically modified seed would be unlikely to increase profits.

• Thus, for most of the feed-corn farmers, changing to genetically modified corn seeds for farming would not likely to lead to higher profits.

Conclusion: For most feed-corn farmers, switching to genetically modified seed would be unlikely to increase profits.

Pre-thinking


Falsification scenario

In what scenario - switching to genetically modified seed would likely increase profits?
Given that:
(i) Genetically modified seeds have a higher resistance to insect pests.
(ii) Yields from genetically modified seeds + less quantity of insecticide = Yields from ordinary seeds + usual amount of insecticide.
(iii) Ordinary seeds are cheaper than genetically modified seeds.
(iv) Savings on pesticides are rarely more than the extra cost for genetically modified seeds.

Though Process
The author talks about two types of corn seeds: genetically modified seeds and ordinary seeds.
The amount of pesticide used with genetically modified seeds is less than the amount of pesticide used with ordinary seeds. However, the yields from both types of seeds are the same. Also, the cost of ordinary seeds is less than the cost of genetically modified seeds. And the savings on the pesticide used with genetically modified seeds are rarely less than the extra cost of the genetically modified seeds. Thus, the author does not believe that using genetically modified seeds will lead to increased profit.

Falsification condition 1: What if the amount of pesticide used last season was more than the amount required with genetically modified seeds?
Let's say the amount of pesticide used last season, although lower than the usual amount, was more than the optimal amount required with genetically modified seeds. Using an even lesser quantity of pesticides will reduce the cost further. This condition would lead to an increase in profits.

Assumption 1: The quantity of pesticide used by farmers with genetically modified seeds last season, was optimal.

Falsification condition 2: What if using genetically modified seeds significantly reduces other agricultural costs?
Let's say the cost of water, the cost of fertilizers etc. is significantly less when genetically modified seeds are used. This condition will lead to increased profits when using genetically modified seeds.

Assumption 2: Using genetically modified seeds does not significantly reduce other agricultural costs.

Answer Choice Analysis

(A) Whether there are insect pests that sometimes reduce feed-corn yields, but against which commonly used insecticides and the genetic modification are equally ineffective INCORRECT
• The evaluation question of this option will provide information about insect pests which are not relevant to the passage. The passage talks about a specific type of insect pest and how they affect yields from two different kinds of seeds.
• The passage talks about the profitability of using one of the two seeds.
• Therefore, this choice is incorrect.


(B) Whether the price that farmers receive for feed corn has remained steady over the past few years INCORRECT
• If the price of the feed corn has remained steady, then the selling price would not necessarily be different for both types of seeds since the option talks about the past few years. The profits could be comparable if the selling price is the same.
• If the price of feed corn has not remained steady, then the price could either have gone up or gone down. In either case, the profit or loss would not be different for both types of seed.
• Hence, this choice is incorrect.


(C) Whether the insecticides typically used on feed corn tend to be more expensive than insecticides typically used on other crops INCORRECT
• This information is irrelevant to the passage because the passage is not concerned about the price of insecticides used on other crops.
• This choice is incorrect.


(D) Whether most of the farmers who tried the genetically modified corn last season applied more insecticide than was actually necessary CORRECT
• This option is directly in line with our pre-thinking assumption 1.
• Variance test
o Yes - Most of the farmers who tried the genetically modified corn last season applied more insecticide than was actually necessary.
o This would weaken our belief in the conclusion because this case would falsify the conclusion.
o No - Most of the farmers who tried the genetically modified corn last season did not apply more insecticide than was actually necessary.
o This would mean that the quantity of insecticide used would have been optimal, and there is no possible way to increase profits. This strengthens our belief in the conclusion.
o This choice is the correct answer.


(E) Whether, for most farmers who plant feed corn, it is their most profitable crop INCORRECT
• The passage is about the profitability of genetically modified seeds over ordinary seeds. Whether feed corn is the most profitable crop or not is irrelevant to the passage.

GMATNinja karishma can you shed some light on A? I didn't understand the explanation from MPrep..

The author concludes that “for most feed-corn farmers, switching (from ordinary seed) to genetically modified seed would be unlikely to increase profits.” So, the author compares the profitability of ordinary seeds with that of genetically modified seeds. The prompt then asks us for an answer choice that helps to evaluate the argument. With that in mind, here’s (A):

The author’s conclusion contrasted the profitability of two types of seed. But (A) gives information on insect pests against which genetically modified and ordinary seeds are equally ineffective. Because the answer choice indicates that both types of seed are equally ineffective against these pests, whether they exist or not, (A) does not help to evaluate the argument, and we can eliminate it.

I hope that helps!

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