Critical Reasoning

Two decades after the Dead Sea Barrier was built, none of the eight sea slug types indigenous to the Dead Sea was still growing adequately in the Sea on one side of the barrier. Since the barrier reduced the annual range of salinity (percentage of salt) in the Sea on one side of the barrier from 30% to 6%, scientists have hypothesized that sharply rising salinity must be involved in signaling the indigenous types of slugs to begin the growing cycle.


Which of the following statements, if true, would most strengthen the scientists' theory?
Choices
A
The indigenous sea slug types could still grow only on one side of the barrier, where the yearly salinity range remained 30%.

B
Before the barrier was constructed, the Dead Sea overflowed its shores yearly, creating salt licks that became key feeding spots for the indigenous type of sea slug.

C
Before the barrier was built, the lowest recorded salinity of the Dead Sea was 16%, whereas after the barrier was built, the lowest recorded salinity of the Sea has been 25%.

D
Non-indigenous types of sea slug, introduced into the Dead Sea after the barrier's construction, started competing with the declining indigenous sea slug types for salt.

E
Of the sea slug types indigenous to the Dead Sea, six are not indigenous to any other sea in the Middle East.

Barrier -> Sea slugs growth affected
Barrier -> Reduces Salinity

Salinity must be involved in Slug growth -> Conc

----------------------------------------------
C,D and E -> Irrelevant

Let's discuss A and B


A The sea slugs can still grow on one side of the barrier where salinity is 30% and not the other where salinity is 6%. Definitely salinity is responsible for growth.IMO A

B This is a very interesting choice. I'll tell you why in the end. (Although, at first I picked this one;))

However, Before the barrier was constructed, dead sea overflowed and created salt licks, that became key feeding spots for sea slugs. No1. This choice lays emphasis on Barrier and not salinity. After the barrier was constructed, the Dead sea did not overflow and hence no salt licks. But what about the portion of water with 6% salinity. I guess that was under discussion. No2. Salt licks can be created with 6% salinity as well. There is nothing here that talks about salt licks created with 6% saline water or 30%. No3. The sea licks became feeding spots. We have no information "signaling the indigenous types of slugs to begin the growing cycle." (Last Line). Well I think I've been thinking too much over this choice, primarily because I picked this one first.

Ok, I said 'interesting' because of this posts' similarity to the question below -

Two decades after the Emerald River Dam was built, none of the eight fish species native to the Emerald River was still reproducing adequately in the river below the dam. Since the dam reduced the annual range of water temperature in the river below the dam from 50 degrees to 6 degrees, scientists have hypothesized that sharply rising water temperatures must be involved in signaling the native species to begin the reproductive cycle.

Which of the following statements, if true, would most strengthen the scientists' hypothesis?

(A) The native fish species were still able to reproduce only in side streams of the river below the
dam where the annual temperature range remains approximately 50 degrees.26
(B) Before the dam was built, the Emerald River annually overflowed its banks, creating
backwaters that were critical breeding areas for the native species of fish.
(C) The lowest recorded temperature of the Emerald River before the dam was built was 34
degrees, whereas the lowest recorded temperature of the river after the dam was built
has been 43 degrees.
(D)Nonnative species of fish, introduced into the Emerald River after the dam was built, have
begun competing with the declining native fish species for food and space.
(E) Five of the fish species native to the Emerald River are not native to any other river in
North America

Please correct me if I'm wrong.

Two decades after the Dead Sea Barrier was built, none of the eight sea slug types indigenous to the Dead Sea was still growing adequately in the Sea on one side of the barrier. Since the barrier reduced the annual range of salinity (percentage of salt) in the Sea on one side of the barrier from 30% to 6%, scientists have hypothesized that sharply rising salinity must be involved in signaling the indigenous types of slugs to begin the growing cycle.


Which of the following statements, if true, would most strengthen the scientists' theory?
Choices
A
The indigenous sea slug types could still grow only on one side of the barrier, where the yearly salinity range remained 30%.

B
Before the barrier was constructed, the Dead Sea overflowed its shores yearly, creating salt licks that became key feeding spots for the indigenous type of sea slug.

C
Before the barrier was built, the lowest recorded salinity of the Dead Sea was 16%, whereas after the barrier was built, the lowest recorded salinity of the Sea has been 25%.

Both options B&C are irrelevant since we have to consider the time since the barrier was built. Not before it was built.

D
Non-indigenous types of sea slug, introduced into the Dead Sea after the barrier's construction, started competing with the declining indigenous sea slug types for salt.


Does not indicate/state any direct relationship between the competition and its resultant effect on the growth cycle of the indigenous sea slug.
E
Of the sea slug types indigenous to the Dead Sea, six are not indigenous to any other sea in the Middle East.

Irrelevant, we are not interested in the habitat of the sea slug.

Hence, by elimination one is left with A. What is the OA?

Hi Charu & Tarun,

Sorry for late reply.

The OA is A .


Charu,

what is the OA of the Q u have posted below?

is it B ??

Two decades after the Dead Sea Barrier was built, none of the eight sea slug types indigenous to the Dead Sea was still growing adequately in the Sea on one side of the barrier. Since the barrier reduced the annual range of salinity (percentage of salt) in the Sea on one side of the barrier from 30% to 6%, scientists have hypothesized that sharply rising salinity must be involved in signaling the indigenous types of slugs to begin the growing cycle.

Which of the following statements, if true, would most strengthen the scientists' theory?
Choices

A The indigenous sea slug types could still grow only on one side of the barrier, where the yearly salinity range remained 30%.

B Before the barrier was constructed, the Dead Sea overflowed its shores yearly, creating salt licks that became key feeding spots for the indigenous type of sea slug.

C Before the barrier was built, the lowest recorded salinity of the Dead Sea was 16%, whereas after the barrier was built, the lowest recorded salinity of the Sea has been 25%.

D Non-indigenous types of sea slug, introduced into the Dead Sea after the barrier's construction, started competing with the declining indigenous sea slug types for salt.

E Of the sea slug types indigenous to the Dead Sea, six are not indigenous to any other sea in the Middle East.

my take is A . though i didn't find the language of the premise very comfortable .this particular expression was troubling me : none of the eight sea slug types indigenous to the Dead Sea was still growing adequately in the Sea on one side of the barrier

as per me ,we don't need "still" in that line .the fact is that after building the barrier none of the species was growing adequately and so the argument concluded that because the salinity has reduced so this reduction of salinity must be a cause for the effect . now the word "still" gives me notion that this growth was not happening ever prior to building of the the barrier ,which might not be the case . in fact it might just be that prior to building of the barrier the growth was very much happening .
instructors plz help me with this
thanks and regards
aditya

Hi Himu,

The answer for this question is A -

Two decades after the Emerald River Dam was built, none of the eight fish species native to the Emerald River was still reproducing adequately in the river below the dam. Since the dam reduced the annual range of water temperature in the river below the dam from 50 degrees to 6 degrees, scientists have hypothesized that sharply rising water temperatures must be involved in signaling the native species to begin the reproductive cycle.

Which of the following statements, if true, would most strengthen the scientists' hypothesis?

(A) The native fish species were still able to reproduce only in side streams of the river below the
dam where the annual temperature range remains approximately 50 degrees.

(B) Before the dam was built, the Emerald River annually overflowed its banks, creating
backwaters that were critical breeding areas for the native species of fish.

(C) The lowest recorded temperature of the Emerald River before the dam was built was 34
degrees, whereas the lowest recorded temperature of the river after the dam was built
has been 43 degrees.

(D)Nonnative species of fish, introduced into the Emerald River after the dam was built, have
begun competing with the declining native fish species for food and space.

(E) Five of the fish species native to the Emerald River are not native to any other river in
North America

To Tommy Wallach
good day sir,
good i had asked this question else my comprehension would have remained wrong life long !! your terse and accurate reply was right on the spot and proved how wrong was my comprehension
thanks a ton
regards
aditya