Summarize Argument: Phenomenon-Hypothesis
The author concludes that industrial by-products have entered the swamp’s ecosystem. This is based on the following:
Some industrial by-products cause elevated hormonal activity.
Recently, some reptiles in this swamp had abnormal development that occurs only with elevated hormonal activity.
Identify and Describe Flaw
The author assumes that there’s no other cause of the elevated hormonal activity besides the industrial by-products. This overlooks the possibility that the reptiles’ hormonal activity could be due to something else, in which case, we cannot conclude that industrial by-products have entered the swamp.
A
provides no explanation for developmental abnormalities that do not result from elevated hormonal activity
The argument concerns abnormalities that are caused only be elevated hormonal activity. Other abnormalities don’t have any impact on the reasoning.
B
fails to consider whether elevated hormonal activity can result from factors other than the presence of industrial by-products
If elevated hormonal activity can result from things besides industrial by-products, then the elevated hormonal activity that the reptiles in the swamp have does not prove that there are industrial by-products in the swamp. The elevated hormones might result from other things.
C
fails to address the possibility that industrial by-products were contained in food the alligators ate
The author doesn’t make any assumption about exactly how the by-products got into the reptiles in the swamp. Maybe the reptiles ate food in the swamp, and that food contained the by-products. This doesn’t undermine the author’s reasoning.
D
fails to say whether reptiles other than alligators were examined for the same developmental abnormalities that were discovered in the alligators
We know there are reptiles in the swamp with the abnormalities that are only caused by elevated hormonal activity. Whether there are other reptiles that have those abnormalities or not has no impact on the reasoning.
E
uses evidence drawn from a sample of alligators that is unlikely to be representative of alligators in general
The conclusion doesn’t concern alligators in general. So there’s nothing flawed about relying on evidence drawn from a sample of alligators in the swamp.
Note: This is video #2 in a two-part explanation using the split approach for comparative passages. In the previous video, J.Y. already tackled whatever questions he could based solely on a readthrough of Passage A. In this video, he picks up with Passage B and then cleans up the remaining questions. So, if you don't see a full explanation for a given question in this video, it's because J.Y. tackled that question in the previous video. (Press shift + ← to head to the previous video.)
Note: This video deals with Passage A only. In this video, J.Y. uses the split approach for comparrative passages. This means he reads through Passage A and then makes a first pass through the questions, answering them to the extent possible based solely on the information in Passage A. For an explanation of Passage B and the remaining unsolved questions, head to the next video (shift + → on your keyboard).
Summary
Many homeowners add commercial fertilizer to their lawns to keep them healthy.
Lawn soil needs macronutrients and micronutrients to remain healthy long-term.
Widely available commercial fertilizers only contain macronutrients.
Raking up grass clippings instead of letting them decay in the soil depletes soil’s micronutrients.
Lawn soil needs macronutrients and micronutrients to remain healthy long-term.
Widely available commercial fertilizers only contain macronutrients.
Raking up grass clippings instead of letting them decay in the soil depletes soil’s micronutrients.
Very Strongly Supported Conclusions
If homeowners rake their grass clippings instead of letting them decay, then widely available commercial fertilizer alone is not enough for their soil to remain healthy long-term.
Homeowners who use widely available commercial fertilizer and also rake their grass clippings need to use another source of micronutrients in order for their soil to remain healthy long-term.
Homeowners who use widely available commercial fertilizer and also rake their grass clippings need to use another source of micronutrients in order for their soil to remain healthy long-term.
A
There is no single fertilizer that provides both the macronutrients and micronutrients necessary for maintaining soil’s long-term health.
Unsupported. “Widely available commercial fertilizers” do not provide both the macronutrients and micronutrients necessary for soil’s long-term health. But this doesn’t mean that no fertilizer provides all necessary nutrients.
B
The macronutrients nitrogen, phosphorus, and potassium are available to homeowners only in commercial fertilizers.
Unsupported. These macronutrients are available to homeowners in commercial fertilizers, but they might be available in other fertilizers or methods too.
C
Widely available commercial fertilizers are not alone sufficient to maintain a healthy balance of nutrients in soil for lawns where grass clippings are not allowed to decay and return to the soil.
Very strongly supported. Widely available commercial fertilizers only provide macronutrients, and soil needs both macro and micronutrients. Since raking grass clippings depletes micronutrients, commercial fertilizers alone are not enough to keep the soil healthy in these lawns.
D
For soil to remain healthy in the long term, it requires the regular addition of both commercial fertilizers and a source of micronutrients such as grass clippings that are allowed to decay and return to the soil.
Unsupported. Commercial fertilizers provide macronutrients and decaying grass clippings provide micronutrients. But these might not be the only sources of nutrients. There could be other methods, like using compost or manure, that also allow soil to remain healthy long-term.
E
Homeowners who rake up their grass clippings are unable to maintain the long-term health of the soil in their lawns and gardens.
Unsupported. Raking up grass clippings depletes soil’s micronutrients, but there might be other sources of micronutrients that homeowners can use to maintain the long-term health of their soil.