Acquiring complete detailed information about all the pros and cons of a product one might purchase would clearly be difficult and expensive. It is rational not to acquire such information unless one expects that the benefits of doing so will outweigh the cost and difficulty of doing so. Therefore, consumers who do not bother to acquire such information are thereby behaving rationally.

The conclusion of the argument is properly drawn if which one of the following is assumed?

A new process enables ordinary table salt to be fortified with iron. This advance could help reduce the high incidence of anemia in the world’s population due to a deficiency of iron in the diet. Salt is used as a preservative for food and a flavor enhancer all over the globe, and people consume salt in quantities that would provide iron in significant amounts.

Which one of the following most accurately describes the role played in the argument by the statement that people consume salt in quantities that would provide iron in significant amounts?

Populations of a shrimp species at eleven different Indonesian coral reefs show substantial genetic differences from one reef to another. This is surprising because the area’s strong ocean currents probably carry baby shrimp between the different reefs, which would allow the populations to interbreed and become genetically indistinguishable.

Which one of the following, if true, most helps to explain the substantial genetic differences among the shrimp populations?

Researchers have studied the cost-effectiveness of growing halophytes—salt-tolerant plant species—for animal forage. Halophytes require more water than conventional crops, but can be irrigated with seawater, and pumping seawater into farms near sea level is much cheaper than pumping freshwater from deep wells. Thus, seawater agriculture near sea level should be cost-effective in desert regions although its yields are smaller than traditional, freshwater agriculture.

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

Researcher: Every year approximately the same number of people die of iatrogenic “disease”—that is, as a direct result of medical treatments or hospitalization—as die of all other causes combined. Therefore, if medicine could find ways of preventing all iatrogenic disease, the number of deaths per year would decrease by half.

The reasoning in the researcher’s argument is flawed because the argument fails to consider that