Sunflowers growing in pots were placed, with their roots submerged, in the pond contaminated with radioactive elements. The sunflowers kept growing; in the process, they absorbed radioactive elements. Within twelve days, 85 percent of the radioactive elements were removed from the water, which is no less than can be accomplished with the much more expensive conventional filtration techniques. Scientists therefore propose using sunflowers for decontamination wherever there are radioactively contaminated ponds.

Which of the following, if true, points to a limitation on the applicability of the proposed method of decontamination?

Secret passwords are often used to control access to computers. When employees are allowed to make up their own passwords, they are likely to setup as passwords their initials or birth dates. To improve security, employers should assign randomly generated passwords to employees rather than allowing employees to make up their own

Which of the following, if true, most seriously undermines the conclusion drawn above?

It is crucially important to farmers that the herbicides they use to control weeds do not damage their crops. One very effective herbicide is safe for corn, but soybeans are damaged even by the herbicide's residue, which remains in the soil more than a year after the herbicide is applied. Soybeans and corn are not sown together in the same field; nevertheless, most farmers are reluctant to use the herbicide on their corn.

Which of the following, if true, provides the strongest justification for the farmers' reluctance?

Rail Executive: Five years ago we discontinued train service between Lamberton and its suburbs because low ridership caused total fares collected to be substantially lower than the cost of operating the service. It is true that recent population growth in the suburban communities suggests increased potential ridership. Nevertheless, since most of the newer residents own automobiles, restoring the train service this year would still result in serious deficits

Which of the following ,if true casts the most serious doubt on the rail executive's argument?

Which of the following most logically completes the argument?

A significant number of Qualitex Corporation's department heads are due to retire this year. The number of employees other than current department heads who could take on the position of department head is equal to only about half of the expected vacancies. Oualitex is not going to hire department heads from outside the company or have current department heads take over more than one department, so some departments will be without department heads next year unless Qualitex ______.

Business Analyst: National Motors began selling the Luxora-its new model of sedan-in June. Last week, National released sales figures for the summer months of June, July, and August that showed that by the end of August only 80,000 Luxoras had been sold. Therefore, National will probably not meet its target of selling 500,000 Luxoras in the model's first twelve months.

Which of the following would be most useful to establish in order to evaluate the analyst's prediction?

Although most smoking-related illnesses are caused by inhaling the tar in tobacco smoke, it is addiction to nicotine that prevents most smokers from quitting. In an effort to decrease the incidence of smoking-related illnesses, lawmakers in Sandonia plan to reduce the average quantity of nicotine per cigarette by half over the next five years. Unfortunately, smokers who are already addicted to nicotine tend to react to such reductions by smoking correspondingly more cigarettes.

The information above most strongly supports which of the following predictions about the effects of implementing the Sandonian government's plan?

Lightbox, Inc., owns almost all of the movie theaters in Washington County and has announced plans to double the number of movie screens it has in the county within five years. Yet attendance at Lightbox's theaters is only just large enough for profitability now and the county's population is not expected to increase over the next ten years. Clearly, therefore, if there is indeed no increase in population, Lightbox's new screens are unlikely to prove profitable.

Which of the following, if true about Washington County, most seriously weakens the argument?

Over the past five years, the price gap between name-brand cereals and less expensive store-brand cereals has become so wide that consumers have been switching increasingly to store brands despite the name brands' reputation for better quality. To attract these consumers back, several manufacturers of name-brand cereals plan to narrow the price gap between their cereals and store brands to less than what it was five years ago.

Which of the following, if true, most seriously calls into question the likelihood that the manufacturers' plan will succeed in attracting back a large percentage of consumers who have switched to store brands?

From 1980 to 1989, total consumption of fish in the country of Jurania increased by 4.5 percent, and total consumption of poultry products there increased by 9.0 percent. During the same period, the population of Jurania increased by 6 percent, in part due to immigration to Jurania from other countries in the region.

If the statements above are true, which of the following must also be true on the basis of them?

Economist: Tropicorp, which constantly seeks profitable investment opportunities, has been buying and clearing sections of tropical forest for cattle ranching, although pastures newly created there become useless for grazing after just a few years. The company has not gone into rubber tapping, even though greater profits can be made from rubber tapping, which leaves the forest intact. Thus, some environmentalists conclude that Tropicorp has not acted wholly out of economic self-interest. However, these environmentalists are probably wrong. The initial investment required for a successful rubber-tapping operation is larger than that needed for a cattle ranch. Furthermore, there is a shortage of workers employable in rubber-tapping operations, and finally, taxes are higher on profits from rubber tapping than on profits from cattle ranching.

In the economist's argument, the two boldfaced portions play which of the following roles?

Shipping Clerk: The five specially ordered shipments sent out last week were sent out on Thursday. Last week, all of the shipments that were sent out on Friday consisted entirely of building supplies, and the shipping department then closed for the weekend. Four shipments were sent to Truax Construction last week, only three of which consisted of building supplies.

If the shipping clerk's statements are true, which of the following must also be true?

Commercially available chemical fertilizers contain the same nutrients and micronutrients as organic fertilizers such as manure and composted garden clippings. Plants have tiny root hairs that absorb nutrients, and whether the source of the nutrients is organic or chemical is irrelevant to the plant's ability to take in the nutrients. Nevertheless, organic fertilizers are better for the health of the plant than are chemical fertilizers alone.

Which of the following, if true, would most strongly support the position above?

Since 1995, Congress has exempted oil companies that have leases issued by the federal government allowing them to drill for deep-water oil off the Gulf of Mexico from royalty payments as an incentive to spur development in times of low oil and gas prices. These leases were supposed to have included a provision that reinstates the royalties should the market prices of oil and gas exceed a certain level. Because of an error by the federal government, however, the language that reinstates the royalties is missing from the more than 1,100 leases issued by the U.S. government in 1998 and 1999. Since the market price of oil and gas has recently risen far above the threshold levels, this error could allow the oil companies to reap a windfall of more than $10 billion through the life of the leases. In response, the government is pressuring the oil companies to renegotiate the leases. The executives of the oil companies strongly oppose renegotiation; all have issued statements stating that they expect the government to honor the terms of the contracts and that renegotiating a duly signed agreement would set a bad precedent.

Which of the following statements best reflects the position of the oil company executives?

The children in the second grade at a local elementary school scored lower on tests of math skills this year than the second graders did last year. The school board blames the disappointing results on the budget cuts that forced the school to consolidate several classes of second-grade students, thus depriving them of the individualized attention that they had previously enjoyed.

Which of the following, if true, best supports the explanation offered by the school board for the students' lower test scores?