Logical Reasoning

PT135 · S1 · Q13 Researchers have studied

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Researchers have studied the cost-effectiveness of growing halophytes—salt-tolerant plant species—for animal forage.

Conclusion

Seawater agriculture near sea level should be cost-effective in desert regions.

Evidence

There are some salt-tolerant plant species, halophytes, that require more water than normal crops but can be irrigated with seawater. It's cheaper to pump seawater into farms near sea level, than to pump freshwater from deep wells.

Evaluate

We're trying to analyze whether this agricultural plan will be cost-effective, which really means will it be profitable -- will the expected revenue at least exceed the expected costs.

All we know is that one cost (watering the plant) will be more expensive in one sense (higher quantity needed) but less expensive in another sense (the type of pumping is cheaper).

The author seems to be assuming that what we'd spend in having to give these plants more water would be matched or exceeded by what we'd save in terms of getting to use a seawater pump rather than a deep freshwater pump.

If we wanted to argue that this wouldn't be cost-effective, we could bring up all the unmentioned factors that go into an agricultural enterprise:

will the other expenses, such as seed / manual labor / equipment / energy for the equipment, be paid for by eventual revenue? is there a market for halophytes? do animals like eating them? would farmers buy halophytes for their animals?

Goal

I'd be going to the answers with almost no specific goal in mind. We just need some more reason to think that raising halophytes by the seaside, using a pump to irrigate with seawater, would be a cost-effective (i.e. profitable) enterprise.

13.

Which one of the following, if true, most strengthens the argument above?

  1. A given volume of halophytes

    Unclear Impact: different

    We would be interested in knowing how the nutritional value compares, since that relates to how much of a market there would / wouldn't be for halophytes. But since this answer just tells us the nutritional value is significantly different, we don't know if it's different for the better or for the worse. Hence, we have no idea whether this helps or hurts.

    4% picked this

  2. Some halophytes not only tolerate

    Too Weak / Irrelevant

    A statement as weak as "some" is almost always wrong on Strengthen, Weaken, and Paradox, where we want answers with the most impact. The fact that at least one halophyte requires salt is not really telling us anything about whether this venture would be cost-effective. We cared that they were tolerant of seawater, because that meant we could irrigate with seawater. We don't care if they need it.

    5% picked this

  3. Large research expenditures are needed

    Weakens

    This goes the opposite direction of "cost-effective", because large expenditures are needed to develop the raw materials for this venture.

    1% picked this

  4. Costs other than the costs

    Unclear Impact

    Same issue as with (A) --- different doesn't have a positive or negative valence, so we have no idea whether this is a favorable or unfavorable comparison.

    8% picked this

  5. Correct

    Pumping water for irrigation is

    Why this is right

    We were wondering whether the extra money we'd spend on higher quantity of water would be matched or exceeded by the money we'd save by doing seawater pumping vs. the more expensive deep-drill freshwater pumping. This answer is saying, "Pumping water is one of the biggest cost areas for farming crops for foraging animals!" If seaside agriculture is saving us money on one of the biggest cost areas, that makes us feel-better about the economics of this venture. This answer is essentially taking the one positive thing we knew about seawater agriculture (the pumping is cheaper) and making that evidence even more compelling by telling us how important an expense category that is.

    Skill tested: Strengthen · how this choice captures the argument's function is the move to repeat next time.

    82% picked this

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