broall wrote:
Nature constantly adjusts the atmospheric carbon level. An increase in the level causes the atmosphere to hold more heat, which causes more water to evaporate from the oceans, which causes increased rain. Rain washes some carbon from the air into the oceans, where it eventually becomes part of the seabed. A decrease in atmospheric carbon causes the atmosphere to hold less heat, which causes decreased evaporation from the oceans, which causes less rain, and thus less carbon is washed into the oceans. Yet some environmentalists worry that burning fossil fuels may raise atmospheric carbon to a dangerous level. It is true that a sustained increase would threaten human life. But the environmentalists should relax—nature will continually adjust the carbon level.
Which one of the following, if true, would most weaken the argument in the passage?
(A) Plant life cannot survive without atmospheric carbon.
(B) It is not clear that breathing excess carbon in the atmosphere will have a negative effect on human life.
(C) Carbon is part of the chemical “blanket” that keeps the Earth warm enough to sustain human life.
(D) Breathing by animals releases almost 30 times as much carbon as does the burning of fossil fuels.
(E) The natural adjustment process, which occurs over millions of years, allows wide fluctuations in the carbon level in the short term.
Source: LSAT
Short Story : 1. Nature constantly adjusts the atmospheric carbon level.
2. /\ in the level causes the atmosphere to hold more heat, which causes more water to evaporate from the oceans, which causes /\ rain.
3. Rain washes some carbon from the air into the oceans, where it eventually becomes part of the seabed.
4. \/ in atmospheric carbon causes the atmosphere to hold less heat, which causes decreased evaporation from the oceans, which causes less rain, and thus less carbon is washed into the oceans.
5. some environmentalists worry that burning fossil fuels may raise atmospheric carbon to a dangerous level.
6. sustained increase would threaten human life.Conclusion : Environmentalists should relax—nature will continually adjust the carbon level.
The question asks to find the statement which
most weakens the conclusion.(A) Plant life cannot survive without atmospheric carbon.Out of scope. As the passage says that the level of carbon will be maintained by nature.
(B) It is not clear that breathing excess carbon in the atmosphere will have a negative effect on human life.Breathing excess carbon in atmosphere will have -ve effect on human life. So, it surely is a problem. But if nature will maintain the level of carbon in atmosphere, there won't be any problem. This doesn't weaken the conclusion.
(C) Carbon is part of the chemical “blanket” that keeps the Earth warm enough to sustain human life.This is again a fact but it doesn't weaken the conclusion.
(D) Breathing by animals releases almost 30 times as much carbon as does the burning of fossil fuels.Breathing by animals releases almost 30 times as much carbon as by burning the fossil fuel. But it is happening from ages. Only extra burden is created by the burning of fossil fuel and hence it has created problem. So this statement is out of scope.
(E) The natural adjustment process, which occurs over millions of years, allows wide fluctuations in the carbon level in the short term.Now this point really weakens the conclusion. Since nature adjustment process will take million years and hence short term fluctuation in carbon level is allowed by nature. So, during that time, the increased level of carbon in nature will threaten human life & hence environmentalists should not relax.
So, my answer is E. Waiting for OA to be posted.
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24 Sep 2017, 23:56
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