The advent of chemical fertilizers led the farmers in a certain region to abandon the practice of periodically growin...

smilde11 on October 24, 2018

PT 73, S2, Q20

I don't understand how B is not correct. Could you please explain? Thank you!

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Mehran on October 24, 2018

Hi @smilde11, thanks for your post. Let's first assess the stimulus. This one presents an argument; the conclusion is "to significantly improve the soil structure, farmers will need to abandon the use of chemical fertilizers." What premises are provided in support of this claim? Well, you are told that in a certain region (1) the introduction of chemical fertilizers led farmers to abandon the practice of periodically growing a "green manure" crop in a field to rejuvenate the soil, and (2) as a result, the soil structure in a typical farm field is poor.

But notice how the stimulus never says the farmers *had* to abandon their practice of growing "green manure" crops, right? Put differently, why can't farmers use chemical fertilizers AND ALSO periodically grown "green manure" crops?

Because the stimulus does not account for this possibility, the argument it presents is weak. It assumes that EITHER farmers will use chemical fertilizers OR farmers will grow "green manure" crops.

The question stem is a Strengthen With Necessary Premise question ("argument relies on the assumption that"). On such questions, negating the correct answer choice will lead the argument in the stimulus to fall apart. The correct answer is (E). Let's negate it: "many, if not all, farmers in the region *will* grow green manure crops *even if they also* use chemical fertilizers." If this is true, then the conclusion in the stimulus falls apart - farmers need not abandon chemical fertilizers to improve soil structure. They can both use chemical fertilizers AND periodically grow their "green manure" crops.

Answer choice (B) is incorrect because it conflates the two concepts set up as a false dichotomy in the stimulus. Whether or not chemicals are applied to green manure crops is besides the point. The argument in the stimulus says you CANNOT have both chemicals and green manure crops, so (B) is irrelevant. To strengthen the argument in the stimulus, you need to bolster this dichotomy (i.e., it's either chemicals OR green manure crops).

Hope this helps! Please let us know if you have any additional questions.