CLAIM:
1) We either have to irrigate the largest affected corn fields –or—
2) Fail to irrigate now and ensure inflation later

Basically, this argument is saying, irrigate OR ELSE! We need to find an answer that shows us that irrigation is the ONLY MEANS of averting inflation.

GOAL:
Find an answer that proves that it’s irrigate or else suffer inflation.

THE OPTIONS:

A. other American agricultural areas are also not expected to meet their anticipated corn yields this year
Wrong: Shade of Gray. If other areas are also not expected to meet their anticipated yields, would that prove that we either have to irrigate or face inflation later? It points us in the right direction, but it doesn’t PROVE that we either need to irrigate or face inflation later. This is what we’d like to call a shade of gray answer.

B. irrigation is the only way that the national corn yield can be significantly increased
YES! This answer proves that we either need to irrigate or face inflation later, because this answer tells that there is no other means.

C. the heat wave and drought will persist through the next two years
Wrong: Shade of Gray. If the heat wave and drought will persist for through the next two years, would that prove that we either have to irrigate or face inflation later? No. This answer tells us that similar conditions will persist, but it doesn’t prove that we HAVE TO irrigate to stave off inflation.

D. irrigation will insure [ensure] that corn harvests reach normal levels
Wrong: Shade of Gray. Obviously, this adds support that irrigation works, but does this prove that we either that we either have to irrigate or face inflation later? This answer might seem tempting, but it only shows that irrigation can work, but NOT that irrigation is the ONLY way. There could be many other ways in addition to irrigation that could ensure that corn harvests reach normal levels. So saying that irrigation will ensure that corn levels reach normal levels does NOT actually prove that its irrigation or else.

E. it is politically feasible for government authorities to spend money irrigating fields at the present time[/quote]
Wrong: Out of Focus. Does this prove that we either that we either have to irrigate or face inflation later? Even if there were funding available, helps only addresses the likelihood of feasibility, but that wouldn’t prove that we either have to irrigate or face inflation later.

Correct Answer: B. It is the only option that proves that its irrigation or else face inflation.

A side note: this is a pretty rare variation of an assumption question on the GMAT, known as a SUFFICIENT assumption question. We’re asked to find the assumption that’s sufficient for the argument to hold. GMAT assumption questions almost always ask us to find an answer taken for granted by the argument, also known as a NECESSARY assumption. SUFFICIENT Assumption questions ask us to find an assumption that essentially proves the argument, so they require a different framework to select the right answer than the typical GMAT style assumption question.

Necessary assumption questions are FAR more frequently found on the LSAT.

Also note, the context here would mean the word “insure” would have to be “ensure”.
_________________

The drought in the central part of the country is estimated to reduce this year's national corn harvest by more than one-third from its normal levels. Such a shortfall would subsequently increase meat and other food prices by about 17% in one year and 20% in two years. So, either we spend a small amount now to irrigate the largest affected corn fields and avert severe inflation later, or else fail to irrigate now and insure inflation later.

The argument is valid only if

other American agricultural areas are also not expected to meet their anticipated corn yields this year
irrigation is the only way that the national corn yield can be significantly increased
the heat wave and drought will persist through the next two years
irrigation will insure that corn harvests reach normal levels
it is politically feasible for government authorities to spend money irrigating fields at the present time

I need help to decide bw B and D

The argument evaluation:

The drought reduce this year's national corn harvest by more than normal level => increase meat and other foods prices by 17% in one year, 20% in two year.
Therefore, irrigating the largest affected corn fields will avert severe inflation latter

A. other American agricultural areas are also not expected to meet their anticipated corn yields this year=> out of scope
B. irrigation is the only way that the national corn yield can be significantly increased
C. the heat wave and drought will persist through the next two years => irrelevant
D. irrigation will insure that corn harvests reach normal levels
E. it is politically feasible for government authorities to spend money irrigating fields at the present time => out of scope

Only choice B and D are the contenders. Negating choice B and D, we will have:

B. Irrigation is not the only way that the national corn yield can be significantly increased => the argument is corrupted.
D. Irrigation will not insure that corn harvests reach normal levels => the conclusion of the argument does not mention whether or not the national corn yield will reach the normal level, but avert (stop) the inflation that is increasing.

=> choice B is the correct one.

With this kind of question, we can see how important the argument's conclusion is. So, learn to understand completely the argument's conclusion.
_________________

Initially chose D. But then on re-reading made me understand my mistake: I missed normal levels.
For those who are on same lines on which I was earlier, here is the easy solution. In the premise, its stated that the corn levels have reduced to one third of their normal levels. Let the normal level be 100. Now negate B, we get that irrigation will ensure that corn harvests don't get to their normal level. What if the corn harvests reach upto 99, then the conclusion doesn't fall apart.
but if there are several other ways that the national corn yield can be significantly increased, then even if we don't spend much on irrigation then also we can't ensure inflation. The conclusion falls apart and hence the answer is B.
_________________

A - slightly out of context.
B - possible.
C - possible.
D - possible.
E - out of context. no mention of politics in the passage.

Basic POE gives me B, C, and D. I have a 33% chance of nailing this problem...

Looks like we can knock C out of the running. We could experience inflation without a two year drought.

So 50% chance.

Looks like B will be the answer as the conclusion of the passage does indeed imply that irrigation is the only solution.

OA...B
yay!

Straight (B)
..." either we spend a small amount now to irrigate the largest affected corn fields and avert severe inflation later, or else fail to irrigate now and insure inflation later"

Means:- The dependency of a good crop depends solely upon the irrigation.

So,to increase the corn yield , irrigation is the only ideal option .

I chose "C" first but on re-reading, B makes complete sense.

The drought in the central part of the country is estimated to reduce this year's national corn harvest by more than one-third from its normal levels. Such a shortfall would subsequently increase meat and other food prices by about 17% in one year and 20% in two years. So, either we spend a small amount now to irrigate the largest affected corn fields and avert severe inflation later, or else fail to irrigate now and insure inflation later.

The argument is valid only if

A. other American agricultural areas are also not expected to meet their anticipated corn yields this year -Okay, let them not meet their target. Out of scope.
B. irrigation is the only way that the national corn yield can be significantly increased -The conclusion says that either irrigate the fields and decrease the inflation or suffer at the hands of increased inflation. It means that only irrigation can decrease the inflation.
C. the heat wave and drought will persist through the next two years -Okay, it is a fact set. Out of scope
D. irrigation will insure that corn harvests reach normal levels -Nowhere in the argument it's written that the harvests will reach normal levels. Out of scope
E. it is politically feasible for government authorities to spend money irrigating fields at the present time -Out of scope

The conclusion comes after the keyword “so.” The author believes that if money is spent to irrigate corn fields, inflation will be averted. If money is not spent to irrigate, inflation is a given. The author's evidence is that there is a drought now that will reduce the corn harvest, which will increase food prices over the next two years.

Predict the Answer:

Note the chain of causation in the evidence. Drought leads to corn shortfall, which leads to increased corn prices, which leads to increased food prices. The author focuses on avoiding the corn shortfall and concludes that the corn fields have to be irrigated. The author must believe that irrigating the corn fields is the only way to avoid the corn shortfall.

Evaluate the Answer Choices:

(B) is a perfect match for the prediction arrived at in Step 3. The author must believe there is no other way to increase the corn yield besides irrigation. (B) is the answer.

(A) is irrelevant. The author focuses on the central part of the country, and the effect the drought in that part of the country will have on the economy. What will happen in other areas has no impact on the author's argument. Eliminate (A).

(C) is not something the author must be assuming. The entire argument is about the effects of the current drought, regardless of how long it lasts into the future. Eliminate (C).

(D) is extreme. The author doesn't have to assume that irrigation will ensure corn harvests reach normal levels. The author is concerned because the drought will reduce the corn harvest “by more than one-third from its normal levels.” The author believes irrigation will solve the problem, but that doesn’t have to mean normal harvest levels. Perhaps irrigation will bring the harvest to 75% of normal levels, or 85%, and that this would be enough to solve the problem. Eliminate (D).

(E) is irrelevant because the author doesn't care who will or could pay for the irrigation, just that if it is done, inflation will be avoided, and that if it isn't done, inflation will come. Eliminate (E).

TAKEAWAY: Be very clear on the evidence and conclusion of the argument, and stick to the connection between them. Irrelevant choices are quite common and can be easily spotted by having a good paraphrase of the argument.
_________________

Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________