Investigation of the floor of the Black Sea, a saltwater sea connected

This strategy is amazing. I am bad in evaluate CR questions. Think this strategy will help me! Thanks souvik101990!

Glad I posted this Q here.

Great explanation by both of you as well! +1

One of the strategies which I use and was taught by e-gmat class was the variance test.

Whatever question is asked in the option , answer as Yes and again answer as No, the conclusion will be different in two cases. Variance means there will be a variation of the conclusion.

For example, lets take the correct option E)
E) Whether the remains of the saltwater creatures found in the sediment closely resemble the remains of Mediterranean saltwater creatures from the same period.
lets say yes, there were remains -> Proves the hypothesis is correct.
Lets say No, there were no remains -> proves the hypothesis is incorrect.
So there is a variation of conclusion. Hence the correct answer.

Copying other expert's explanation from other forum is not a good practice unless we mention the name of that expert.

Majority of explanations are provided by me. Are you pointing to me?

The hypothesis that water from medeterrian flew to black sea would be more easily answered if we know any proof and option E presents one such proof like situation of whether the creature remains of the two seas bear any resemblance if answer is yes then yes water might have flown. This is the only choice asking about such possibility .Hence E is the answer.

Phew.., took me 5 mins to answer the question, but got it right.

I wonder if there is a simpler or quicker way to answer questions of this kind. Questions such as this take a lot of time in the real GMAT. By the way what is the level of scoring for this question.

Thank you for posting such a nice question. A good brainer.

this question is hard b/c it is hard to catch the main idea of the argument, and how the option choices directly relate to the argument.

C and D are surely out of scope.
B and E are closed, but A also is a trap.
A is actually irrelevant b/c of "body of fresh water whose shorelines", B is not good enough and B is not so clear to be an assumption.

B sea is far from all other seas except M sea to which it connects by a narrow channel.
B sea's floor was investigated (dug up to see the composition of layers under the floor)
We found freshwater shells dating from 5500 B.C. on an ancient shoreline 500 ft below current floor level.
The layer just above this ancient shoreline had saltwater remains.

Hypothesis: About 5500 B.C., seawater from the Mediterranean overflowed into the Black Sea basin.

All data points toward it, right? B sea is connected to M sea only. Before 5500 BC, B sea had fresh water (so it must not have been connected to any sea at that time). Then M sea must have overflowed into it because of which it got seawater & seawater creatures.

What will help us evaluate whether it was M sea that overflowed into it around 5500 BC?

A. Whether the body of freshwater whose shoreline was uncovered was less than 500 feet deep

The depth of the body at that time is irrelevant.

B. Whether the remains of saltwater creatures contained in the layers of sediment that lie just above the ancient shoreline differ significantly from those contained in the topmost of layers of sediment in the floor of the Black Sea

We know that ancient shoreline has freshwater creatures and the layer just above it has seawater creatures. We already know there are different remains in the two layers.

C. Whether any of the freshwater shells show indication of having been used as tools

Irrelevant

D. Whether there are traces of an ancient shoreline of the Black Sea that lies significantly less than 500 feet below the sea'€™s current level

Another ancient shoreline is irrelevant to this argument.

E. Whether the remains of the saltwater creatures found in the sediment closely resemble the remains of Mediterranean saltwater creatures from the same period.

Correct. To evaluate whether it was M sea that overflowed around 5500 BC, we need to know if the creatures in the two seas were similar after overflowing.
If they are similar, it increases the probability that M sea overflowed into B sea.
If they are not similar, it doesn't help our argument. It may not have been M sea that overflowed into B sea.

Answer (E)

Hi souvik101990 - i though option C was legitimate.

If Yes - well, humans were the reason why the freshwater sea shells are at the bottom of the black sea
If No -- this eliminates a possible alternative (possible alternative : humans were using sea shells as tools. Because of humans, you are seeing freshwater sea shells)

While your question wasn't directed towards me, I will give it a shot nonetheless

The hypothesis concerns the remains of seawater creatures - it tries to explain where these came from.

Option C will help us figure out where the freshwater creatures (those lying beneath the seawters creatures' remains) came from. And that isn't going to help us validate the hypothesis. Hence, it's not C.

On the other hand, E gives information that bridges the gap between the investigation's findings and the scientists' hypothesis.

I hope that helps