In the 1960s, surveys of Florida’s alligator population indicated that the population was dwindling rapidly. Hunting alligators was banned. By the early 1990s, the alligator population had recovered, and restricted hunting was allowed. Over the course of the 1990s, reports of alligators appearing on golf courses and lawns increased dramatically. Therefore, in spite of whatever alligator hunting went on, the alligator population must have increased significantly over the decade of the 1990s.

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

Professor: A marine biologist argues that transmission of sea lice from farm salmon to wild salmon is unlikely in the Broughton Archipelago, British Columbia, citing numerous studies suggesting that salinities less than 30 parts per thousand are unfavorable to sea-lice survival. The biologist concludes that the archipelago's 25-30 parts per thousand salinity range between March and June, the critical period for wild salmon migration, tends to suppress sea-lice proliferation. But a review of the literature shows that salinities of 25-30 parts per thousand in combination with British Columbia's cool spring temperatures favor the flourishing of sea lice.

In this passage, the professor attempts to undermine the biologist's argument by

Airline Representative: The percentage of flight delays caused by airline error decreased significantly this year. This indicates that airlines listened to complaints about preventable errors and addressed the problems. Although delays caused by weather and other uncontrollable factors will always be part of travel, preventable delays are clearly decreasing.

Which of the following most clearly points to a logical flaw in the representative 's reasoning?

Educational Theorist: Recent editorials have called for limits on the amount of homework assigned to schoolchildren younger than 12. They point out that free-time activities play an important role in childhood development and that homework in large quantities can severely restrict children's free time, hindering their development. But the actual average homework time for children under 12-little more than 30 minutes per night-leaves plenty of free time. In reality, therefore, the editorials' rationale cannot justify the restriction they advocate.

Which of the following, if true, would most seriously call into question the educational theorist's conclusion?

In the last few years, plant scientists have been able to genetically engineer seeds to produce crops highly resistant to insect damage. Farmers growing crops with these seeds will be able to spend significantly less on pesticides. This cost reduction would more than make up for the higher cost of the genetically engineered seeds. Clearly, therefore, farmers who grow crops from genetically engineered seeds will be able to reduce their costs by using them.

Which of the following. if true, most weakens the argument?

In persons with astigmatism, the clear outer layer of the eye is deformed in a way that impairs and sometimes distorts vision. The elongated figures in the paintings of El Greco (1541-1614) were so unusual that some critics sought to explain them by hypothesizing that without knowing it, El Greco had an astigmatism that caused everything to appear to him in the distorted way that was characteristic of his painted figures.

The proposed explanation is most vulnerable to the criticism that it fails to

Brown tides are growths of algae on the sea's surface that prevent sunlight from reaching marine plants below, thereby destroying not only the plants but also the shellfish that live off these plants. Biologists recently isolated a virus that, when added to seawater, kills the algae that cause brown tides. Adding large quantities of this virus to waters affected by brown tides will therefore make it possible to save the populations of shellfish that inhabit those waters.

Which of the following, if true, provides the most support for the conclusion of the argument?

Highway Official: When resurfacing our concrete bridges, we should use electrically conductive concrete (ECC) rather than standard concrete. In the winter, ECC can be heated by passing an electric current through it, thereby preventing ice buildup. The cost of the electricity needed is substantially lower than the cost of the deicing salt we currently use.

Taxpayer: But ECC is vastly more expensive than standard concrete, so your proposal is probably not justifiable on economic grounds.

Which of the following, if true, could best be used by the highway official to support the official's proposal in the face of the taxpayer's objection?

Manufacturers of mechanical pencils make most of their profit on pencil leads rather than on the pencils themselves. The Write Company, which cannot sell its leads as cheaply as other manufacturers can, plans to alter the design of its mechanical pencil so that it will accept only a newly designed Write Company lead, which will be sold at the same price as the Write Company's current lead.

Which of the following, if true, most strongly supports the Write Company's projection that its plan will lead to an increase in its sales of pencil leads?

Pretzel Vendor: The new license fee for operating a pretzel stand outside the art museum is prohibitively expensive Charging typical prices. I would need to sell an average of 25 pretzels per hour to break even. At my stand outside City Hall, with about as many passers-by as at the art museum, I average only 15 per hour. So I could not break even running a stand outside the art museum, much less turn a proft.

Which of the following, if true, most seriously weakens the pretzel vendor's argument?