GMATNinja I know often times we see the test-takers quickly dismiss a choice because it is 'out-of-scope' ...to me that seems like a cop out (unless it is absolutely clear without a shadow of a doubt, that the choice is in fact irrelevant). Can you elaborate on this thinking?
For example, in this problem a lot of users ruled out a. However, one could argue that cost does play a role here. Suppose that the cost actually increases because of the higher demand...that would disincentivize builders who might then decide to search out cheaper alternatives...Hence if less people are buying the cement, then the idea that atmospheric CO2 will decrease is damaged.
Many industrialized nations are trying to reduce atmospheric concentrations of carbon dioxide, a gas released by the burning of fossil fuels. One proposal is to replace conventional cement, which is made with calcium carbonate, by a new “eco-cement.” This new cement, made with magnesium carbonate, absorbs large amount of carbon dioxide when exposed to the atmosphere. Therefore, using eco-cement for new concrete building projects will significantly help reduce atmospheric concentrations of carbon dioxide.
P: Industrialized nations are trying to reduce carbon dioxide concentrations
P: A proposal is to replace conventional cement with a eco-cement
P: Eco-cement absorbs large amounts of CO2 when exposed to the atmosphere
C: Eco-cement for new concrete building projects will significantly reduce atmospheric CO2
Which of the following, if true, most strengthens the argument?
(A) The cost of magnesium carbonate, currently greater than the cost of calcium carbonate, probably will fall as more magnesium carbonate is used in cement manufacture.
-cost is irrelevant
(B) Eco-cement is strengthened when absorbed carbon dioxide reacts with the cement.
-unnecessary detail that does not affect the conclusion at all
(C) Before the development of eco-cement, magnesium-based cement was considered too susceptible to water erosion to be of practical use.
-irrelevant detail; we aren’t interested in something that came before eco-cement, but whether eco-cement will reduce carbon dioxide in the future
-one might think that since eco-cement represents an improvement over magnesium-based cement that it will reduce CO2…while that’s possible…be wary of trying to make a story fit…
(D) The manufacture of eco-cement uses considerably less fossil fuel per unit of cement than the manufacture of conventional cement does.
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