Self-study
Researchers have studied the cost-effectiveness of growing halophytes—salt-tolerant plant species—for animal forage. ██████████ ███████ ████ █████ ████ ████████████ ██████ ███ ███ ██ █████████ ████ █████████ ███ ███████ ████████ ████ █████ ████ ███ █████ ██ ████ ███████ ████ ███████ ██████████ ████ ████ ██████ █████ ████████ ███████████ ████ ███ █████ ██████ ██ ██████████████ ██ ██████ ███████ ████████ ███ ██████ ███ ███████ ████ ████████████ ██████████ ████████████
Summarize Argument
The author concludes that seawater agriculture should be cost-effective in desert regions near sea level. He supports this by saying that salt-tolerant plants (halophytes) require more water but can be irrigated with seawater, which is much cheaper to pump than freshwater.
Notable Assumptions
The author assumes that seawater agriculture is cost-effective simply because seawater irrigation is cost-effective. He assumes that the benefits of seawater irrigation outweigh any other potential costs of seawater agriculture, like higher fertilizer or equipment costs.
13.
Which one of the following, ██ █████ ████ ███████████ ███ ████████ ██████
a
A given volume ██ ██████████ ██ █████████████ █████████ ██ ███████████ █████ ███ ██████ ██████ ████ ███ ████ ██████ ██ ████████████ ██████ ██████
This doesn't tell us if halophytes are more or less nutritious than conventional crops for animal forage. Knowing they have "significantly different" nutritional value doesn't help to establish that halophytes are more cost-effective.
b
Some halophytes not ████ ████████ ████████ ███ ███████ ████ ██ █████ ██ ███████
The author says that halophytes are salt-tolerant and that they’re more cost-effective because they can be irrigated with seawater. In other words, she already assumes that the plants will be irrigated with salt water. The fact that they require salt is irrelevant.
c
Large research expenditures ███ ██████ ██ ███████ ███ ███████ ██ ██████████ ████ ██████ ███ ████████████ █████████
This weakens the argument by presenting another cost of halophytes. If seawater agriculture requires expensive research, it might not actually be more cost-effective overall.
d
Costs other than ███ █████ ██ ██████████ ███ █████████ ███ ██████████ █████ ██ █████ ██ ████████ ██████████ ████ ███ ████████████ ██████
The fact that other halophyte costs are “different” from conventional crop costs doesn't tell us if halophytes are more or less expensive overall.
e
Pumping water for ██████████ ██ ██████████████ ███ ██ ███ ███████ █████ ████████ ██ ████████ ███████████ ███ ████████████ ███ ██████ ████ ███ ████████
If irrigation is one of the largest costs in producing forage crops, this suggests that seawater agriculture may indeed be more cost-effective in certain areas, since seawater irrigation is much cheaper.