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Critical Reasoning: Conclusion Strengthening Questions

Interested in growing avocados, the owners of a vast produce farm are considering two similarly sized parts of their unused land, each on a completely different part of the farm, to start an avocado field on. An important factor affecting the successful growth of avocado trees, and the fruit they produce, is the population of pests in the area of the field, yet this is less important than whether the soil in the area has a high iron content, iron being the most beneficial nutrient to the plant. To determine which of the two areas would be most profitable to grow avocado trees upon, the owners plan on taking an iron sample from the soil of each area and choosing the area with the highest iron content level based on an analysis of the two samples.

Which of the following, if true, most strengthens the reason to expect that the owner's plan will succeed?

Incorrect.

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This answer choice neither supports nor weakens the owners' plan. The argument does not present details about the sizes of the areas in any of the premises. Therefore, the figure of 30,000 square feet in this question is irrelevant (the areas could be 90,000 square feet each, for example). In such a case, the sample's analysis could turn out to be insignificant.

Incorrect.

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This answer choice weakens the plan put forward by the owners. If low iron amounts just lead to less avocado whereas pests can destroy everything, then it seems that the farm owners should be more worried about the pests than about the iron.

Incorrect.

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We are asked in the question stem to evaluate and strengthen the owners' plan. This answer choice introduces a different factor (sunshine) for analysis, instead of referring to the owners' idea.

Incorrect.

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This answer choice weakens the plan proposed by the owners while we were supposed to support it. If the water supply is also a vital factor, and it is not equal in all parts of the farm, then it needs to be tested too before any decision is made. However, the owners' plan only includes the soil analysis as a condition to decide which area is better for growing avocados. Therefore, this answer choice makes the owners' test seem flawed.

Magnificent!

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This answer choice strengthens the efficiency of the owners' plan. We are told in this statement that to enrich an area without enough iron is far more expensive than to get rid of a really bad pest problem. Therefore, this answer choice supports the idea that testing the amount of iron in each field is the most important test one can do in deciding which field to choose for growing avocados.

Iron content analysis performed using soil samples can precisely determine the iron deposits for an area of up to thirty thousand square feet by taking only a single soil sample.
An insufficient level of iron content in the soil may lead to a low yield of fruit and lower revenues while a pest infestation that is not combated promptly can devastate even a large field in a matter of days.
The costs of treating a heavily pest-infested field and treating one that isn't infested at all, but needs protection, are the same, and are lower than treatments of iron soil supplements.
If the area with the higher iron content also receives more sunshine than the other, another parameter affecting the healthy growth of avocados, then there will be no doubt which should be used for the plantation.
Another vital factor necessary for the growth of avocado trees is an abundant water supply and while the water in the case of the farm in question is supplied to all parts of the farm by the same source, it is not supplied in equal amounts.