Most of the world's supply of uranium currently comes from the mines.

definitely A. It would be economical to use seawater uranium extraction if either cost is reduced or price goes up. The argument states that the cost has to be reduced which is true only is price doesn't go up. Depletion of supply will definitely cause price to go up.

My answer is also A.

If I were a VC and need to start doing the business of extracting uranium from sea water, I will go with A because that is the shortest way to determine the success of my venture. Sure, C also helps, but it takes time. And the question is about 'most useful', hence A wins over C.

i can't understand why A is the answer.. i would choose this option only in a "weaken question", but this is an "evaluation question"; my kaplan book says: "The correct answer won't strengthen or weaken the author's reasoning or supply a missing assumption. Instead, the right answer will specify the kind of evidence that you would help you to judge the validity of the author's argument"
this is the reason why i'd chose C
can someone helps me?

We want to evaluate this:

Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.

Which of the following would it be most useful to determine in evaluating the argument?

a. Whether the uranium in deposits on land is rapidly being depleted
This is the correct answer. If the deposits on land are rapidly being depleted, the uranium's price is going to be higher so despite the high costs, the method of obtaining uranium will be commercially viable.

c. Whether there are any technological advances that show promise of reducing the costs of extracting uranium from seawater
I) show promise of reduce != will reduce
II) determining the possible existence of such technologies does not help us in evaluating the argument
(...) until the cost of extracting uranium from seawater can somehow be reduced (...) <== it has no effect on this

Well this is a toughie.Two options are too close.
Fact 1: Most of the world's supply of uranium currently comes from mines
Fact 2: It is possible to extract uranium from seawater, but the cost of doing so is greater than the price that uranium fetches on the world market.
Conclusion: until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable

A. Whether the uranium in deposits on land is rapidly being depleted
CORRECT.If the uranium in deposits on land is rapidly being depleted then we have no other choice to shift to some other source .Doesn't matter what the cost of extraction is !
B. Whether most uranium is used near where it is mined
Out of scope. We are concerned about price of extraction not transportation cost or any other thing that this argument is hinting.
C. Whether there are any technological advances that show promise of reducing the cost of extracting uranium from seawater
Incorrect.This is tempting.But i believe the argument is made now so we have to check the validity NOW.The future techs are out of scope.
D. Whether the total amount of uranium in seawater is significantly greater than the total amount of uranium on land
Irrelevant. It doesn't matter how large quantity is available in seawater.If the cost of extraction is high,we will not fetch it.
E. Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater
Out of SCOPE.This introduces a new source.We need to evaluate seawater only.

Found a very nice explanation on manhattangmat.
here is the link for that https://www.manhattangmat.com/forums/mos ... t3508.html

whoa, no, guys. that's not the issue here.

the problem is this:

the argument says
until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.

in other words, the argument is saying that the ONLY WAY that seawater extraction will be commercially viable is if the cost of that extraction comes down.

to weaken the argument, then, you need to find ANOTHER way in which seawater extraction will be commercially viable, WITHOUT a cost reduction.
this is what choice (a) does. if the uranium on land is being depleted, then extracting uranium from seawater will become "commercially viable", out of pure necessity. the cost will go up, but that's the breaks.

choice (c) doesn't actually affect the argument at all, because the argument already acknowledges that uranium will become commercially viable IF the price comes down.

--

analogy:
if i tell you this:
unless you eat my fish 'n' chips, you'll never know the true meaning of gastronomic ecstasy

then:
* if you say "eating your fish 'n' chips will give me gastronomic ecstasy", then that doesn't affect my statement at all, because you're just echoing what i've already told you.

however:
* if you say "au contraire, i can also get gastronomic ecstasy from a nice fat slice of meat lover's pizza", then that weakens my argument, because i'm telling you there's only one source of gastronomic ecstasy but you're countering with another.

substitute
fish 'n' chips --> cost increase
pizza --> depletion of land resources
gastonomic ecstasy --> commercially viable
...and there you have it.

This is a great question and I just want to add my two cents to clarify the difference between A & C. I picked A first and then started thinking about C which also makes a lot of sense. But here's my reasoning for why C is definitely wrong.

A) Correct answer because, if land deposits are running out in 10 years then extracting from seawater becomes a necessity. At that point think about supply and demand, when the supply decreases, demand increases and the price goes up. Therefore at some point it becomes commercially viable. Now think about OIL, when the price of oil is $40 a barrel, it becomes commercially unprofitable to dig oil out of Alberta's tar sands, so companies stop extracting it. But when the price goes up, they start extracting because it becomes commercials viable. Demand has a huge impact on the price. Now imagine if all the Oil in the world ran out and we found oil on the Moon, would it become commercially viable to go to the moon? Yes, people would start going to the Moon to get oil. So think about that.

For C) many people are stuck with this option, I also thought this might be correct BUT, think about the supply. IF the supply of land uranium is unlimited, it will never run out, so even if there's new technology then that technology might make it cheaper to extract from land. (There is a lot of uncertainty). So think in terms of extremes, unlimited resources on land, therefore we may never have to extract from water, even if it becomes cheaper than it was before. Say Extracting from land = $1, and extracting from water = $10, even if the cost of extracting from water comes down to $5 with new technology, its still cheaper to get it from Land. So without knowing the cost of each method and supply, we can't answer with C.

So the answer is A. Hope this helps!

why not (b)? since most of the uranium is used where it is mined then there can be reason to extract uranium at those places where there are no mines to meet the local demand making it commercially viable.

You mentioned that we need to evaluate along the COST, PRICE line. In that case why is C wrong which says the the cost will decrease based on technological advancements

Consider the following argument:

If you go to the beach today, you will get a sunburn.

You might respond, "You're wrong. I'm not going to the beach today, so I won't get a sunburn." But that doesn't matter. The argument states that IF you go to the beach today, you will get a sunburn. Whether you actually go has no impact on the logic.

Similary, the conclusion here is:

"Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable".

It doesn't matter if or when the cost of extracting uranium from seawater can be reduced. Maybe that cost will go down sometime soon, maybe it will go down a few decades from now, and maybe it will never go down... all that matters is that UNTIL that cost goes down, that method of obtaining uranium is unlikely to be commercially viable.

I hope that helps!

Can someone please shed light on options A and C? i just think both are right.

The argument concludes that "until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable." In other words, if the price of extracting uranium from seawater does not decrease, then obtaining uranium from seawater will not be commercially viable.

Keeping in mind that we’re looking for an answer choice that would help evaluate that argument, here’s (C):

I’m going to steal heavily from my previous post here, but consider the following argument:

If you go to the beach today, you will get a sunburn.

You might respond, "You're wrong. I'm not going to the beach today, so I won't get a sunburn." But that doesn't matter. The argument states that IF you go to the beach today, you will get a sunburn. Whether you actually go has no impact on the logic.

Similary, the conclusion here is:

"Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable."

When evaluating the argument at hand, it doesn't matter if the cost of extracting uranium from seawater DOES decrease because the author is arguing about what will happen if the cost DOES NOT decrease. All that matters is that UNTIL the cost goes down, obtaining uranium from seawater is unlikely to be commercially viable. Eliminate (C).

And here’s (A):
Again, I’ll borrow from my previous post here. According to the author, the only way that extracting uranium from seawater will become commercially viable is if the COST of that method is decreased. But what if the PRICE that Uranium fetches on the world market increases? In that case, the seawater method could become commercially viable even if the cost does not decrease.

In order to evaluate the author's argument, we would want to know whether the price of Uranium is likely to increase. (A) tells us that the supply of uranium from land deposits is rapidly decreasing, so the price of uranium will presumably rise. Therefore, (A) tells us about the future price of uranium and is the best choice.

I hope that helps!

One could also argue here that the proximity of the land mines determines the total cost (of extraction plus transportation), and that can be useful to determine to compare with the same cost for water-sourced uranium.

GMATNinja GMATNinja2 ?

It is true that knowing whether most uranium is used near where it is mined could shed some light on transportation costs of uranium. However, the problem is that whether those costs are low or high, the cost extracting uranium from seawater is still too high to be commercially viable. So, (B) does not help address the heart of the passage.

For further explanation on why we can eliminate (B), check out this post.

egmat GMATNinja EMPOWERgmatVerbal ExpertsGlobal5

Option A does not affect the argument but option C does + nowhere in option A is it mentioned that price of uranium will increase in future if there is depletion of resources on land. Maybe an alternative is discovered because of which people stop using uranium.

The correct answer choice doesn't need to PROVE whether we'll start extracting uranium from seawater. Instead, it just needs to help us evaluate how UNLIKELY it is that we'll do so before the cost comes down.

(A) does exactly that. If uranium deposits on land are rapidly being depleted, then it's MORE LIKELY that it will be commercially viable to extract uranium from seawater even if it remains expensive to do so. If they are NOT rapidly being depleted, then the author's argument stands. That's why (A) is the correct answer.

Regarding an alternate source of energy: that's totally compatible with the author's argument. If we top using uranium altogether, then the price of extraction seawater uranium won't come down, and it won't be commercially viable.

For an explanation of why (C) is incorrect, check out this post and let us know if you have any further questions.

I hope that helps!

Currently uranium comes from mines (deposits on land) and fetches say $100 per pound.
Uranium can be extracted from sea water but that is expensive (say cost of extracting one pound is $150) . So this method is not commercially viable.

Conclusion: If the cost of extracting uranium from seawater is not reduced, this method will remain commercially non - viable.

Since in case of seawater method, cost > price uranium fetches, the method is not viable.
What can make the method viable? Either cost of extraction reduces (to below $100 per pound) or price of uranium in the market increases (to above $150 per pound)
The conclusion says that cost of extraction must reduce. What will help us in evaluating it? What will help us find whether the conclusion makes sense i.e. whether cost must reduce to make it viable? We must find out whether price can increase to above $150 or not.
If price in market will remain at $100, then cost of extraction must come below $100 to make it viable.
If price in the market increases substantially, the cost of extraction may not have to reduce and it may still become viable.

(A) Whether the uranium in deposits on land is rapidly being depleted

If uranium on land is depleting rapidly, then price of uranium is likely to increase rapidly in the future and the seawater method may become viable.
If land deposits are huge and many, then price of uranium is likely to stay steady in the future and to make seawater method viable, cost of extraction must reduce. Hence, this option will help us in evaluating whether cost must reduce to make the method viable.

(B) Whether most uranium is used near where it is mined

Where uranium is used is irrelevant.

(C) Whether there are any technological advances that show promise of reducing the costs of extracting uranium from seawater

We need to find whether we need to reduce cost of extraction from seawater. Whether we have any promises tech to do that currently or not is irrelevant.

(D) Whether the total amount of Uranium in seawater is significantly greater than the total amount of uranium on land

The comparison of amount of uranium in seawater vs that on land is out of scope for us. We are discussing cost of extraction vs price in the market.

(E) Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater

Freshwater is out of scope.

Answer (A)