#24 - Many homeowners regularly add commercial fertilizers

[Administrator]

Complete Question Explanation

Must Be True. The correct answer choice is (C)

This stimulus presents information about the nutrients required for lawns to remain healthy. Many homeowners regularly add commercial fertilizers to their lawns and gardens, so that they can maintain a healthy balance of nutrients in the soil. However, it appears that using these commercial fertilizers isn’t enough. The widely available commercial fertilizers contain only macronutrients, namely nitrogen, phosphorus, and potassium. However, to remain healthy in the long term, soil for lawns requires more than just macronutrients. It also requires trace amounts of micronutrients such as zinc, iron, and copper. The micronutrients are depleted when grass clippings are raked up rather than allowed to decay and return to the soil.

This is a Must Be True question. The correct answer to this question will contain either an inference possible from a combination of the facts presented in the stimulus, or it will contain only a restatement of one of those facts. Here, an inference from a combination of the facts is possible. As described above, since the widely available commercial fertilizers do not contain trace amounts of micronutrients, then using only these fertilizers is not enough to maintain a healthy lawn over the long term. Some source of the listed micronutrients must be used in addition to the commercial fertilizer.

Answer choice (A): The stimulus said only that the widely available commercial fertilizers do not contain trace amounts of certain micronutrients. This fact does not preclude the possibility that some single fertilizer, though not a widely available, commercial fertilizer, contains both the macronutrients and micronutrients necessary for maintaining soil’s long-term health.

Answer choice (B): This answer choice is incorrect, because it is a reversal of the information in the stimulus. The facts in the stimulus were that the widely available commercial fertilizers contain only macronutrients. It did not say that the macronutrients are available only in commercial fertilizers.

Answer choice (C): This is the correct answer choice. As described above, the stimulus stated that for a lawn to remain healthy long term, both certain macronutrients and trace amounts of certain micronutrients are required. The widely available commercial fertilizers do not contain the micronutrient trace amounts, and raking up grass clipping prevents the clippings from returning the micronutrients to the soil. So, the widely available commercial fertilizers are not 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.

Answer choice (D): The stimulus did not identify commercial fertilizers as the only source of the required macronutrients. Thus, it is not supported to say that commercial fertilizers are required for soil to remain healthy in the long term. Rather, it is providing a regular source of the listed macronutrients and trace amounts of the listed micronutrients.

Answer choice (E): Similarly to the issue of macronutrients and commercial fertilizer in answer choice (D), the stimulus did not establish that grass clippings are the only source of the trace amounts of micronutrients required for having a healthy lawn in the long term.

[lsatqueen]

Please help; why is the answer C and not D? I am very confused as to why this is incorrect, namely because it seems that the wording of D mirrors exactly what the stimulus says.

[Adam Tyson]

Careful there, Your Highness - does answer D really mirror the stimulus? Far be it from me to disagree with your royal personage, but if you would indulge me I will try to explain my humble self.

The stimulus says that healthy soil need both macro- and micronutrients. It also tells us that commercial fertilizers have those macronutrients and that grass clippings have the micro ones. But does it say that healthy soil needs commercial fertilizers? No, my liege, it does not!

Here's a quick analogy for you: I need chocolate in order to stay happy, and M&Ms have chocolate in them. Do I need M&Ms to stay happy? Nope - they might help, but so might a Hershey bar or a brownie or some chocolate ice cream. It's not the M&Ms that I need but the chocolate found in them, much like soil doesn't need commercial fertilizers but rather the macronutrients found in them.

By your leave, Highness, and may it please you greatly. All hail to the Queen!

[avengingangel]

Thanks for the explanation. I agree that D is wrong, but with C is still confusing because the stimulus says that macronutrients are used "to maintain a healthy balance of nutrients in soil." The argument then proceeds to make a distinction, and notes that additionally trace amounts of micros are needed for long-term health. But answer choice C is not talking about what's sufficient for long-term health, it's just trying to maintain the healthy balance!!!

[Adam Tyson]

I think you might be looking at a distinction without a difference there, avengingangel. The author tells us that the commercial fertilizers have only one kind of nutrient, and soil needs another kind as well in order to stay healthy. That's enough for us to conclude that the commercial fertilizers do not provide a "healthy balance", because they are unbalanced, missing something essential to long term health. Don't get too picky about them using different terms here! And if micronutrients are required for long term health, doesn't that indicate that their absence is unhealthy? Your analysis depends on their existing some status that could be called a "healthy balance" in the short term that does NOT lead to good health in the long term. I wouldn't call that a healthy balance - I would call that a problem waiting to happen!

[sicm91]

Hi! I am having trouble seeing how E is wrong. Doesn't the stimulus say that people who rake up their grass clippings rather than let them decay will not have enough micronutrients, thus unhealthy soil? Thanks:)

[atierney]

Hi,

For this question, the stimulus tells us that if we don't allow grass clippings to decay, then the soil micronutrients are depleted. And so, we can properly infer that if we don't want soil micronutrients to become depleted, then we must allow the grass clippings to decay. And indeed, if this was what answer choice stated, then I am definitely with you that it would be a correct statement, given the content of the stimulus. HOWEVER, answer choice E goes a step further, and indeed, this step takes us off the ledge! Answer choice E says we are unable to maintain long-term health of the soil, if we don't allow the grass clippings to decay. That's like saying, well if you let your vision decay (I mean let is a rather loose term here), then you will be able to see. But, I could get glasses right? I could get contacts, heck, I could get laser vision surgery. In other words, the depletion of the healthy state does not equate to the maintenance of a long-term health, since it presumes that once depleted, there is no way to get it back. I mean, you can look to your favorite (only) DC comic book character's nemesis, Bane, we can always climb our way out!

Let me know if that makes sense. Basically, it's the idea that answer choice E falsely equates the depletion of the nutrients with the failure to maintain health in the long-term, i.e. it failed to consider affirmative acts you could take to restore nutrients lost.

[Snomen]

My reasoning for eliminating C was Necessary indicator "requires" from the Stimulus. I diagramed it like this: HLT→MAC and MIC. So, I eliminated C because I thought that they were Necessary conditions, not a Sufficient ones. Can anyone please correct me here? Where did I make mistake?

[Robert Carroll]

Snomen,

Answer choice (C) says that the widely available commercial fertilizers are not alone sufficient, so the fact that certain things are necessary doesn't really seem to be a problem with this answer. If two things are separately necessary for another thing, then neither alone is sufficient - that's exactly avoiding a Mistaken Reversal, not committing one, because it's denying that a necessary condition is sufficient. If MAC and MIC are both necessary for HLT, then surely neither one is alone sufficient for HLT. But that's what answer choice (C) says.

Robert Carroll