sayan640 wrote:
Hi
VeritasKarishma or
GMATNinjaCan you please tell as to which one is correct A or E ?
Also some explanations for all the options will be helpful...
Can you please throw some light ?
(A) is the correct answer. To see why, let's break down the information in the passage.
The first sentence sets conditions for the growth of algae:
Quote:
Microscopic plants called algae grow inside the top layer of sea ice in the Antarctic if enough sunlight reaches that layer of ice and enough seawater, which contains nutrients, reaches that layer after splashing onto the surface.
From this, we know that the algae require "enough" of both sunlight and seawater to grow. Notice that we don't know exactly how much is "enough" -- we just know that the algae requires both of these things. In addition, we know that the seawater contains nutrients.
Now, on to the paradox:
Quote:
Even though moderate snow cover reduces the sunlight that filters into the top layer, sea ice with moderate snow cover typically contains even more algae in the top layer than does sea ice with less snow cover.
Somehow, the algae grow better in moderately snow-covered ice, which receives
less sunlight than does ice with less snow on top. Remember that the algae require "enough" sunlight in order to grow -- so, the reduced amount of sunlight filtering through the snow must still be enough for the algae to grow. The answer choice that "most helps explain this apparent discrepancy" should explain why the algae grow better in the snow-covered ice.
Take a look at (A):
Quote:
(A) As the weight of accumulated snow forces ice lower in the water, more seawater splashes onto the surface and seeps through the snow.
(A) tells us that the moderately snow covered ice gets splashed with more seawater than does other ice. We know from the passage that seawater is required in order for the algae to grow, and that it contains nutrients. So, the ice covered by snow still receives "enough" sunlight, and in addition is splashed by more nutrient rich sea water. This definitely resolves the apparent discrepancy. (A) is our answer.
Now look at (E):
Quote:
(E) More sunlight filters through a layer of ice than through an equally thick layer of snow.
This passage compares the algae in a top layer of ice with "moderate snow cover" to the algae in a top layer of ice with "less snow cover." The key difference is the amount of
snow on the
top layer of ice. Answer choice (E) compares a layer of ice covered by snow to a layer of ice covered by... another layer of ice? In this case, we are no longer addressing the top layer of ice, which is at the heart of the discrepancy in the passage.
In addition, answer choice (E) states that more sunlight gets through the ice than the snow -- which could lead one to believe that the algae would grow more readily under ice than under snow. This is essentially the opposite of what we need. We are trying to understand how more algae could grow under
more snow.
For these reasons, (E) is out.
I hope that helps!
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