Solutional caves are formed in the earth when a soft rock, usually limestone, is eroded by rainwater that has mixed with soils and carbon dioxide to form carbonic acid. Troglotopia Cave and the surrounding earth contain low amounts of soft rock, so it is not a solutional cave.

For purposes of evaluating the argument it would be most useful to establish which of the following?

Genetically modified crops have been sold commercially for almost twenty years now, and there is no evidence linking their consumption with any sort of disease. At this point, it is unreasonable to believe they are dangerous; with such attention on them, if they created short- or long-term health problems, we would know about it by now.

Which of the following, if true, most weakens the argument stated above?

Since publicly traded companies opt to shield some negative information about their company from the market, negative information tends to be shared progressively less and in wider communication channels of a company's organization. The public is, therefore, has less negative information about a publicly traded company than do the company's employees of the most private circles, such as the CEO.

The conclusion drawn above is based on the assumption that

If the city goes on polluting the air at present rates, air quality and visibility over the city will begin to suffer, rainwater may be polluted, and the city will contribute to the global problem of greenhouse emissions. Taxing every polluting commercial establishment per volume of polluted air or per particulate volume of greenhouse emissions will induce businesses to reduce the amount of pollution they emit; this charge will therefore protect the city's air.

Which of the following is an assumption made in drawing the conclusion above?

Disease X has afflicted cattle and cut into ranchers' profits. A genetic cause of the disease has been identified, as well as a gene therapy that can completely eradicate the cause of the disease in cattle. By applying this gene therapy to their cattle and eradicating the genetic susceptibility to the disease, ranchers will be able to carry on business in the future without incidence of Disease X in their cattle.

Which of the following is an assumption on which the argument depends?

Which of the following most logically completes the passage?

A tropical thorn forest was cleared and converted by humans into soybean fields. The loss of the original habitat poses a threat to the area's population of cuis, which are wild guinea pigs. Ecologists originally estimated that the cuis in the area would vanish within four years. Two years later, the population of cuis is already cut in half, but it is unlikely that they will completely vanish from the region within the next two years, since _______________.

Nanotechnology may pose risks in the coming decades as we find it increasingly commonplace to introduce small robots into our bodies. But the fact that these robots might be invisible to the naked eye doesn't mean we are helpless against them. After all, since the initial development of germ theory, we have designed and continuously improved upon ways to protect ourselves from a variety of germs.

In the passage, the author develops the argument by

The more incentives there are for financial institutions to provide home mortgages, the more mortgage options financial institutions will provide to cater to different circumstances, and the odds that a potential home buyer is able to purchase a home are increased when more mortgage options are available. Therefore, by increasing incentives to financial institutions to provide home mortgages, the government can create circumstances that are more helpful for home buyers.

If the statements above are true, which of the following must be true?

In the shipping industry, the amount of time it takes for most of a worker's occupational knowledge and skills to become obsolete has been declining because of the introduction of wearable computing devices, such as smart watches and smart glasses. Given the rate at which wearable computing devices are currently being introduced into shipping, the average worker's old skills become obsolete and new skills are required within as little as two years.

Which of the following plans, if feasible, would allow a company to prepare most effectively for the rapid obsolescence of skills described above?

A study this year found that, among citizens of Tamalia whose tax reports were selected at random for an audit, 21 percent had prepared their taxes with the assistance of a tax accountant. However, among those whose audits uncovered indications of potential tax fraud, only 3 percent had prepared their taxes with the assistance of a tax accountant. Clearly, citizens of Tamalia who prepare their taxes without the assistance of a tax accountant are more likely to commit tax fraud.

The conclusion drawn above depends on which of the following assumptions?

Springfield's city council wants to minimize the city's average yearly expenditures on its parking meters and so is considering replacing the coin-operated meters currently in use with roadside kiosks at which parking slips can be purchased via credit card. Since many of the coin-operated meters require replacement, the costs associated with the conversion to credit card kiosks would be minimal.

Which of the following would it be most useful to know in determining whether switching to roadside kiosks would be likely to help minimize Springfield's yearly maintenance costs?

Which of the following expressions is equivalent to $\frac{{18}^{20}-{18}^{19}}{34}$?