Which of the following most logically completes the argument?

Researchers recently asked dozens of shoppers, chosen at random coming out of a FoodBasket supermarket, what they had purchased. The prices of the very same items at the nearest ShopperKing supermarket were totaled and compared with the FoodBasket total. The ShopperKing totals averaged five percent higher than the FoodBasket totals. Nevertheless, this result does not necessarily show that shoppers at ShopperKing would save money overall by shopping at FoodBasket instead, since __________.

In the United States, of the people who moved from one state to another when they retired, the percentage who retired to Florida has decreased by three percentage points over the past ten years. Since many local businesses in Florida cater to retirees, this decline is likely to have a noticeably negative economic effect on these businesses.

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

Personnel officer: The exorbitant cost of our health-insurance benefits reflects the high dollar amount of medical expenses incurred by our employees. Employees who are out of shape, as a group, have higher doctor bills and longer hospital stays than do their colleagues who are fit. Therefore, since we must reduce our health-insurance costs, we should offer a rigorous fitness program of jogging and weight lifting to all employees, and require employees who are out of shape to participate.

The conclusion reached by the personnel officer depends on which of the following assumptions?

Political advocacy groups have begun to use information services to disseminate information that is then accessed by the public via personal computer. Since many groups are thus able to bypass traditional news sources, whose reporting is selective, and to present their political views directly to the public, information services present a more balanced picture of the complexities of political issues than any traditional news source presents.

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

From 1973 to 1976, total United States consumption of cigarettes increased 3.4 percent, and total sales of chewing tobacco rose 18.0 percent. During the same period, total United States population increased 5.0 percent.

If the statements above are true, which of the following conclusions can be properly drawn?

In a study conducted in Pennsylvania, servers in various restaurants wrote "Thank you" on randomly selected bills before presenting the bills to their customers. Tips on these bills were an average of three percentage points higher than tips on bills without the message. Therefore, if servers in Pennsylvania regularly wrote "Thank you" on restaurant bills, their average income from tips would be significantly higher than it otherwise would have been.

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

Newspaper editorial:
In an attempt to reduce the crime rate, the governor is getting tough on criminals and making prison conditions harsher. Part of this effort has been to deny inmates the access they formerly had to college-level courses. However, this action is clearly counter to the governor's ultimate goal, since after being released from prison, inmates who had taken such courses committed far fewer crimes overall than other inmates.

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

The growing popularity of computer-based activities was widely expected to result in a decline in television viewing, since it had been assumed that people lack sufficient free time to maintain current television-viewing levels while spending increasing amounts of free time on the computer. That assumption, however, is evidently false: in a recent mail survey concerning media use, a very large majority of respondents who report increasing time spent per week using computers report no change in time spent watching television.

In order to evaluate the argument, it would be most useful to determine which of the following?

The emission of sulfur dioxide when high-sulfur coal is burned is restricted by law. New coal-burning plants usually comply with the law by installing expensive equipment to filter sulfur dioxide from their emissions. These new plants could save money by installing instead less expensive cleaning equipment that chemically removes most sulfur from coal before combustion.

Which of the following, if known, would be most relevant to evaluating the claim above about how new coal-burning plants could save money?

Outbreaks of Rift Valley fever occur irregularly in East Africa, several years apart. When outbreaks do occur, they kill thousands of cattle. A livestock vaccine against the disease exists but is rarely used. It is too expensive for farmers to use routinely, and since it is not effective until a month after vaccination, administering it after an outbreak begins helps very little. Nevertheless, experts predict that use of the vaccine will increase significantly within the next few years.

Which of the following, if true, provides the strongest justification for the experts' prediction?