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?