In the late nineteenth century, the archaeologist Charles

This question is a bit awkward as it's not a great representation of a GMAT question (it looks like it's from the Economist?)

Anyway, as the prior posts indicate, removing 3 of the 5 options is relatively easy (very common on CR questions) and we are left with 2 options that both seem to be possible answers, A&C. On Critical Reasoning, you want to get rid of the garbage (obviously wrong answers) quickly so you can spend time working on the 2 possible answers.

Let's dig into A&C. The premise of the argument presents an approach of digging deep vertical shafts connected to tunnels that will reach previously unaccessible areas. The conclusion is that the same method can be used to reach sunken artifacts (under water). What is the necessary assumption between A & C? Let's try negating...

Negated A - The specific weight of water and earth are not similar, thus creating different pressure on the tunnel's ceiling.
If there is different pressure between the tunnels under ground and under sea and there is more pressure under sea, might the under sea tunnels collapse and prevent reaching the sunken artifacts? Very possibly.
Negated C - Tunnels beneath the seafloor and tunnels beneath dry land do not share the same vertical distance from the surface.
Does the distance to the surface impact the ability to dig shafts connected to tunnels? The premise states that the underground tunnels are "deep" under the earth so it appears that depth doesn't impact the ability to use this technique.

Normally with negation we get the destruction of the conclusion. I wouldn't say that negated 'A' destroys the conclusion, but it seems to do much more harm to the conclusion than negated 'C', so we will choice answer choice A.

KW

There are certainly a lot of issues in this question - the argument says that shafts may be dug, leading to tunnels. So it seems like the tunnels already exist and can be accessed easily - all you have to do is dig deep shafts to access them. If that is the case, the specific weights of water and earth don't come in the picture. The tunnels are there - you just access them by digging a hole at some point. Whatever the weight above them, they are already supporting it.
Another case is where you dig deep shafts and then dig in some way to get access to the tunnels. If that is the case, you need to be careful about the weight above the tunnel you are making. But you may still be able to make them thicker - just like you can make shafts longer or shorter if the depth of sea shore tunnels are different from the depth of dry land tunnels. So neither A nor C is an assumption. If one of them is an assumption, the other becomes an assumption too.
The only reason I may pick A instead of C is that C says 'same vertical distance' and A says 'similar specific weight'. So C is more binding and hence not necessarily true. Also digging deeper may be easier than withstanding higher weight.
Another possibility is that the question implies that due to the higher specific weight, the tunnels may already be blocked at places - for that we need a lot more technical know how of how the tunnels are identified etc which is outside the scope of this argument.

All in all, I wouldn't worry about this question. As Kyle said, it is not representative of actual GMAT questions.

can the moderator remove the questions which are not GMAT? why to have non-gmat question on GMAT Club..its ironical.

I agree that it is a bit ironic that we have so many GMAT questions that don't come from the GMAT itself but there is a good reason for it. There are only so many GMAT questions available for our review that we wouldn't have nearly as many helpful discussions if we were limited to actual GMAT questions. The 'GMAT' questions from other sources are for the most part very representative of an actual GMAT question but now and again you will find examples that aren't super close to the real thing. In those cases you consider the source and move on

KW

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We can easily eliminate choices B,D and E.

Between A and C, we can eliminate C because, the science there is easy and we can guess that it is not because of the same vertical distance, given the information in the passage. There is more science in choice A and it is likely that same pressure on the tunnel's ceiling is needed. So I would chose A.

In my opinion this option "A" contains more of a scientific information "specific weight" which means nothing to the people who do not know what does this term exactly mean. Now even if the specific weight is different, how does it matter? The material of shaft will simply be made of the material that can withstand the pressure exerted by the matter with high specific weight.

Option "C" seems more plausible to me as it is more related to the topic under discussion in general.

I still don't really get how to evaluate each statement.

For A, couldn't you argue that it's irrelevant? Sure common sense might tell you the difference in pressure will lead to tunnels collapsing, and so you won't reach those artifacts, but isn't that kind of a far-fetched conclusion?

For D, if you try negating it > Shafts similar to those dug by the celebrated Warren may NOT be dug on the sea-shore (for whatever reason...) then the conclusion that you can dig these similar shafts in order to reach sunken artifacts falls apart, no?

Is this a general rule we should know, that if a statement is too close to what was said in the argument, it's a no-go? Also, in some other question solutions, statements similar to A, which are common-sense and you might think that's the correct answer, turn out to be "unrelated or irrelevant" because we're jumping one step too far from the actual content.

Please help! Thanks!

I was between A and D and naturally I chose the wrong answer

Can I eliminate D because Warren himself did not dig the tunnels? Is this a valid reason?

This one is actually easy if you diligently follow POE(process of elimination)
Clearly it says - hidden assumption.

What is the hidden assumption underlying Prof. Zweig's hypothesis?
A) The specific weight of water and earth are similar, thus creating the same pressure on the tunnel's ceiling. - sounds Ok
B) Otherwise inaccessible sunken archeological artifacts can be reached using new technological advancements in the world of marine robotics. - weakens
C) Tunnels beneath the seafloor and tunnels beneath dry land share the same vertical distance from the surface. - weakens
D) Shafts similar to those dug by the celebrated Warren may be dug on the sea-shore, enabling archaeologists easy access to otherwise inaccessible sunken archeological artifacts.stated as it is in the conclusion
E) Otherwise inaccessible terrain can be reached below the surface using vertical shafts. - vague assumption

Now coming back to
A) The specific weight of water and earth are similar, thus creating the same pressure on the tunnel's ceiling. - sounds Ok

Lets negate this - doesn't create the same pressure -> now the conclusion that similar process can be used is weakened, hence Option A becomes the right one here. So by POE you could get down to only 1 choice to check.

Hi daagh Sir, @abhimanha,
i got some doubtful points here. As a mechanical engineer just shifted to technology consulting, I am quite interested in these wordings.
point 1 : The argument is on Shafts not tunnels.
point 2 : Terrain : The sea floor is one of the terrain.

A says the tunnels ceiling is under high pressure. So what the shaft inside the tunnel can withstand or not is the point.Lets say, The tunnel will imbue pressure on the shafts and hope the option A talks about pressure on shafts ( as similar shafts are used ). I agree A is right.

E says: These terrains can be reached by vertical shafts. Obviously sea floor can't be reached by horizontal shafts first. They need to be dug by vertical shafts.
Negate it: The inaccessible terrains can not be reached by vertical shafts. BOOM! So The whole conclusion that these similar shafts can be used is doomed (*edited a typo here) as these shafts can never be used. The process itself is flaw to apply here.

Conclusion is not just that shafts can be used but that HYPOTHESIS as a whole.

Can you please tell me where my approach is failing to arrive at right answer ?

Thank you
Best Regards

Since i answered this question correctly here is my reasoning let first part of argument be in blueand second part in the color you see

In the late nineteenth century, the archaeologist Charles Warren discovered a new way to explore otherwise inaccessible areas, using vertical shafts leading to horizontal tunnels deep beneath the surface. These tunnels led directly to those areas.
Based on Warren's discovery, Zachi Zweig, a rising star in the archaeological scene, has concluded that similar shafts may be dug on shores in proximity to sunken archeological artifacts, leading to tunnels beneath the sea floor allowing easy access to those artifacts.

First part - is it mentioned anywhere word "dry" ? archeologist just mentions word "surface"

Second part: conclusion: "similar shafts may be dug on shores in proximity to sunken archeological artifacts, leading to tunnels beneath the sea" so Zachi Zweig mentions that similar shafts can be dug on shores, leading to tunnels

What is the hidden assumption underlying Prof. Zweig's hypothesis?


So A logically fills in missing information. i even didnt understand what is the meaning of "shaft" i just made following assumption, very simple

So, first we talk about some technique digging tunnels under surface IN GENERAL and then we SUDDENLY consider using the same technique under sea.
hence A. because of similar properties of the solid surface of earth and water …. there is no other explanation for this

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