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.

Answer will be posted after discussion!!!

Consider Kudos If my post helps!!!

Archit

Carcass, Can you explain your take......it will really help , if you can explain why not B??????

Hi Carcass
What we are concerned is to strengthen that salt is necessary for the growth of indigenous type of slug...hence If an option says that the salinity helped in the growth of slug....than why should be bothered about the fact that this was few years back or today...I do not think that salinity is going to reduce...even if it does we need just to strengthen that salinity from the water that dam is sufficient for the growth of slug...

Archit

@carcass
good job....what happened decade ego v/s happening today.....
BTW source is grockit.

Archit

I do not think , what distinguishes A from B , as far as correct answer is concerned , is not "what happened decade ago v/s happening today" . But rather A is strengthening the scientist's hypothesis whereas B , in a way , weakens it.

Hypothesis : (now that the barrier is built) Sharply rising salinity is needed in order to get the slug types to grow.

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

Says, on one side where salinity is 30% , they are doing good, indication salinity is what is hampering their growth. So strengthens saying "good we can rise the salinity on the other side too where there is a decrease" , in order to get them to grow again.

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.

Now that the barrier is built , there is no overflow of dead sea and hence no salt lick and hence no feeding spot for sea slug . But now the scientist say that increasing the salinity will help regain their growth. It is a bit of a stretch to assume that increasing salinity will lead to salt lick again and hence increase the feeding spot for sea slug.
Since no information/correlation between salt lick and salinity is given in the argument , if we go by the exact info what is given , we can take these to be two different factors. Hence as per B , it says slug needs those salt lick as feeding spots to enhance their growth rate but scientists are planning to achieve this just by increasing the salinity . Hence, at worst, this option weakens and at best , it is irrelevant.

-Jyothi