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When there is less rainfall than normal, the water level of

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Director
Joined: 02 Sep 2016
Posts: 784

Kudos [?]: 25 [0], given: 275

Re: When there is less rainfall than normal, the water level of [#permalink]

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07 Sep 2017, 10:09
When there is less rainfall than normal, the water level of Australian rivers falls and the rivers flow more slowly. Because algae whose habitat is river water grow best in slow-moving water, the amount of algae per unit of water generally increases when there has been little rain. By contrast, however, following a period of extreme drought, algae levels are low even in very slow-moving river water.

This question first explains a fact and shows cause and effect. Then again a fact about algae and its relation to the fact mentioned in the first sentence.
But to create a little complication, the sentence throws a contrast (HOWEVER).
So we would be asked to find an explanation for this.

Which of the following, if true, does most to explain the contrast described above?

(A) During periods of extreme drought, the populations of some of the species that feed on algae tend to fall.
That means the algae should increase. OPPOSITE.

(B) The more slowly water moves, the more conducive its temperature is to the growth of algae.
SAME AS A.

(C) When algae populations reach very high levels, conditions within the river can become toxic for some of the other species that normally live there.
(D) Australian rivers dry up completely for short intervals in periods of extreme drought.
CORRECT.
Why?
Algae increased…………………..drought came…………….algae decreased………………drought gone…………..algae will start from zero.
So the population stays at the same level.

(E) Except during periods of extreme drought, algae levels tend to be higher in rivers in which the flow has been controlled by damming than in rivers that flow freely.
OUT OF SCOPE. Does not answer the question.

So what I understand is:
This question gives a fact and another fact. Relates the two and then shows a gap which we have to explain.
1) Opposite answers that goes in some different direction without even touching upon what has been asked.
2) Out of scope. No relation to what is happening. Just like that.
_________________

Help me make my explanation better by providing a logical feedback.

If you liked the post, HIT KUDOS !!

Don't quit.............Do it.

Kudos [?]: 25 [0], given: 275

Manager
Joined: 02 Jan 2017
Posts: 90

Kudos [?]: 2 [0], given: 23

Location: Pakistan
Concentration: Finance, Technology
GMAT 1: 650 Q47 V34
GPA: 3.41
Re: When there is less rainfall than normal, the water level of [#permalink]

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14 Dec 2017, 14:23
is this really 650 Level question. ? Didn't feel as such.

Kudos [?]: 2 [0], given: 23

Re: When there is less rainfall than normal, the water level of   [#permalink] 14 Dec 2017, 14:23

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