LR Question 13 Explanation
QUESTION TEXT: Researchers have studied the cost-effectiveness of growing…
QUESTION TYPE: Strengthen
CONCLUSION: Seawater agriculture might work in desert regions near sea level.
REASONING: Halophyte plants can survive on sea water. Halophytes need more water than normal crops, but it’s cheap to pump seawater, compared to pumping from wells.
ANALYSIS: Halophyte irrigation can be cost-effective. Great.
But, irrigation is not the only factor in agriculture. You’ve also got to consider the cost of fertilizer, labor, machines, seeds, transport to market, etc.
The right answer shows that irrigation is a major cost in agriculture. Since halophyte irrigation is cost-effective, this helps show that raising halophytes in desert regions could make sense.
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- The ‘volume’ of food isn’t necessarily relevant. A small volume of meat gives you more calories than an equivalent volume of vegetables. That doesn’t necessarily make meat ‘better’.
The key factor is how much it costs to feed an animal using halophytes, and whether animals can survive on halophytes. This answer doesn’t address those issues. - This is tempting. But the stimulus wasn’t about whether you should irrigate halophytes with salt water. The question was whether to grow halophytes at all.
Halophytes are less productive, but also the only plants that can use seawater. - This weakens the argument. If research spending were required, then that would be an obstacle to making halophyte agriculture work.
- This tells us that costs are different.
But it doesn’t tell us whether halophytes cost more, or less. - CORRECT. We know that irrigation costs are cheaper for halophytes in desert areas. So if irrigation costs are a major part of agricultural costs, then that is a big advantage.
More Resources for Strengthen Questions
- Intro Course lesson: This intro course lesson covers Strengthen questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers strengthen questions.
growing halophytes is affordable because they can be irrigated from seawater. therefore, seawater agri near sea level should be cost-effective.
My prephrase was – well what if the affordability of irrigation doesn’t apply to deserts? I.e. seawater irrigation in general is true for halophytes but it could be the case that it isn’t cost-effective near desert regions
In other words, i noticed a sort of “is” vs. “ought” distinction here i.e. is: halophytes cheaper with seawater, ought: cost-effective in desert regions
I get the cost argument as stated in the right answer choice but that wasn’t my first instinct
Prephrases can be very helpful in speeding us up, but you should be quick to discard them. There can be more than one flaw in the argument.
In this case though, I wouldn’t say the flaw is is/ought, even though they use should. Here, should is used as more of a probability word. For example if I say: “The weather forecast calls for rain, so it should rain tomorrow” –> I mean it is likely to rain, rather than there is a moral imperative for rain.
The argument actually hasn’t proven that seawater irrigation is cost effective anywhere. Deserts aren’t a central issue. We need to establish that irrigation costs are important enough for seawater irrigation to make an impact.
Note: This is an old comment but I wanted to clarify the point.