Ozone in The Stratosphere Blocks Deadly Ultraviolet Rays From The Sun, But Chlorofluorocarbons (CFCs) in Aerosols and Other Products have Thinned this Protective Layer.

Question: Ozone in the stratosphere blocks deadly ultraviolet rays from the sun, but chlorofluorocarbons (CFCs) in aerosols and other products have thinned this protective layer. Evidence of this is the ozone hole that forms over the South Pole every Antarctic spring as temperatures drop below –78°C, the temperature at which ozone depletion occurs. Measurements of the ozone hole taken at various times this spring show that, compared with the same times the previous year, its area diminished by four million square kilometres. Nevertheless, scientists have not concluded that the ozone layer is recovering.

Which of the following would, if true, provide the strongest reason for the scientists' reaction to the measurements?

1. The ozone hole has steadily grown in size every year for the past decade except this year.
2. The length of time that the ozone hole persists fluctuates from year to year.
3. As a result of international treaties, CFCs have been completely banned for several years.
4. Weather patterns allowed unusual amounts of warm air to mix into the polar regions this year.
5. Human-made CFCs retain their ability to destroy ozone molecules for seventy-five to one hundred years.

“Ozone in the stratosphere blocks deadly ultraviolet rays from the sun, but chlorofluorocarbons (CFCs) in aerosols and other products have thinned this protective layer” – is a GMAT Critical question. This particular GMAT Critical Reasoning topic has been taken from the book ‘GMAT Official Guide Verbal Review, 2016 Edition’. This weakens the argument type of GMAT CR question. To answer the question, a candidate can by either finding a piece of evidence that would weaken the argument or logical flaws in the argument. GMAT critical reasoning tests the logical and analytical skills of the candidates. This topic requires candidates to find the strengths and weaknesses of the argument, or find the logical flaw in the argument. The GMAT CR section contains 10 -13 GMAT critical reasoning questions out of 36 GMAT verbal questions.

Answer: D

Explanation: GMAT critical reasoning tests the reasoning skills along with the candidate's logical and analytical thinking abilities. The candidate has to deduce the correct option by finding the logically correct argument.

This question requires us to spot which of the solution choices would supply the strongest reason to support the scientists' scepticism about whether the ozonosphere is recovering.

This scepticism exists despite the actual fact that measurements of the hole taken at various times during the Antarctic spring have shown that the opening has diminished significantly from its size at identical times the previous year.

One major reason to be sceptical would be if there have been some factors aside from a recovery of the ozonosphere that might reasonably account for the diminished size of the outlet.

1. This doesn't give much reason to be sceptical that the ozonosphere is recovering. Certainly one wouldn't want to be too hasty in declaring a recovery after noting a trend of growth within the ozone hole's size. Nevertheless, something must account for this year's divergence from the trend. It seems reasonable to conclude, barring the invention of another factor that will explain the change, that recovery within the layer may be an element during this year's divergence.
2. Each of the measurements was smaller than at the identical time within the previous year. This fact would appear to point that fluctuations within the length of your time the hole persists don't justify the scientists' scepticism.
3. The actual fact that CFCs—which led to the thinning of the ozone layer—have been banned counts against the scientists' scepticism instead of supporting it.
4. Correct. The opening forms when the temperature drops below –78°C during the Antarctic spring. If much of the realm where the opening appears was significantly warmer than the previous year—perhaps above –78°C—there exists a reason apart from a recovery within the ozonosphere that explains the smaller size of this year's hole within the ozone. This might support the scientists' scepticism.
5. whether or not CFCs retain their ability to destroy ozone molecules for several decades, something must account for the decrease in the size of the outlet. Nothing within the passage indicates whether the number of CFCs within the atmosphere has been increasing or decreasing. If it's been decreasing for a protracted time, then this fact is compatible with a belief that the layer is recovering.

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