Some anthropologists study modern-day societies of foragers in an effort to learn about ou

levels that are, on average, much higher than the levels found in older houses. The reason air-pollution levels are higher in the newer houses is that many such houses are built near the sites of old waste dumps or where automobile emissions are heavy. Which of the following, if true, calls into question the explanation above?

A．Many new houses are built with air-filtration systems that remove from the house pollutants that are generated indoors.

B．The easing of standards for smokestack emissions has led to an increase in air-pollution levels in homes.

C．New houses built in secluded rural areas are relatively free of air pollutants.

D．Warm-weather conditions tend to slow down the movement of air, thus keeping pollution trapped near its source.

E．Pressboard, an inexpensive new plywood substitute now often used in the construction of houses, emits the pollutant formaldehyde into the house.

control laws was 645 crimes per 100,000 persons—about 50 percent higher than the average rate in the eleven states where strict gun-control laws have never been passed. Thus one way to reduce violent crime is to repeal strict gun control laws. Which of the following, if true, would most weaken the argument above?

A．The annual rate of violent crime in states with strict gun-control laws has decreased since the passage of those laws.

B．In states with strict gun-control laws, few individuals are prosecuted for violating such laws.

C．In states without strict gun-control laws, many individuals have had no formal training in the use of firearms.

D．The annual rate of nonviolent crime is lower in states with strict gun-control laws than in states without such laws.

E．Less than half of the individuals who reside in states without strict gun-control laws own a gun.

tance that greatly impedes calcium absorption by the body. Therefore, other calcium-containing foods must be eaten either instead of or in addition to spinach if a person is to be sure of getting enough calcium. Which of the following, if true, most seriously weakens the argument above?

A．Rice, which does not contain calcium, counteracts the effects of oxalic acid on calcium absorption.

B．Dairy products, which contain even more calcium than spinach does, are often eaten by people who eat spinach on a regular basis.

C．Neither the calcium nor the oxalic acid in spinach is destroyed when spinach is cooked.

D．Many leafy green vegetables other than spinach that are rich in calcium also contain high concentrations of oxalic acid.

E．Oxalic acid has little effect on the body" s ability to absorb nutrients other than calcium.

s that kill specific weeds but are harmless to grain crops, use a broad-spectrum herbicide effective against all kinds of plants and use genetic engineering specifically to make the crops impervious to the herbicide. Which of the following, if true, is the most serious obstacle to an implementation of the new idea outlined above?

A．Certain herbicides that are effective against specific weeds can inhibit the growth of certain crops as much as two years after application.

B．Research to date suggests that the nutritional properties of crop plants would not improve as a result of the genetic alterations being contemplated.

C．Most herbicides that kill only a narrow range of targets contain active ingredients that are harmful to domestic animals and wildlife.

D．Effective broad-spectrum herbicides are on the market, but their very effectiveness has so far rendered them unsuitable for agricultural weed control.

E．Although genetic modification has made individual plants of grain species resistant to broad-spectrum herbicides, the seeds that such plants produce will not sprout.

ysically fit. But only a small proportion of children ever participate in team sports. Moreover, team sports usually do less to encourage fitness in participants than do physical education programs that focus directly on aerobic exercise. The considerations above, if true, could be used most effectively to argue against

A．the use of in-school physical education programs to encourage lifelong fitness habits in students.

B．the participation by young children in community sports teams.

C．schools" relying heavily on aerobic exercise programs to help all children become physically fit.

D．the use of a large part of a school" s physical education curriculum for team sports.

E．the use of team sports in schools as an occasional activity for talented athletes.

ofit on each. However, FilmPro is losing money because people are buying illegally copied versions of its $ 25 videocassettes at far cheaper prices. So far, one million illegally copied cassettes have been sold for $ 5 each. Illegal copying, therefore, has cost the company at least $ 10 million in potential profits. Which of the following is an assumption that, if true, would allow the conclusion above to be properly drawn?

A．The price of the illegally copied videocassettes never goes below $ 5 apiece.

B．At least one million more cassettes would have been purchased from FilmPro for $ 25 apiece if the illegally copied cassettes had not been available.

C．FilmPro refunds money to customers dissatisfied with the original cassettes.

D．The illegally copied tapes are of such high quality that it is virtually impossible to differentiate between them and the originals.

E．FilmPro never sells discontinued videocassettes at less than $ 25 apiece.

ll of the refined gasoline they sell from Haibei seaports only storage tank, which is always refilled with the same quality of gasoline. Therefore, the brands of gasoline for sale on Haibei may be different in name and price, bat they are identical in quality. The conclusion drawn above depends on which of the following assumptions?

A．Consumers are usually unaware of variations in the quality of the gasoline they buy unless those variations are announced by the gasoline companies.

B．When tankers make gasoline delivery at Haibei" s seaport , the storage tank an Hailed always receives the same quantity of gasoline as that in the preceding delivery.

C．There is a wide variation in the price at which the different brands of gasoline on Haibei are sold.

D．If any gasoline company on Haibei alters the quality of its gasoline before sale, the other gasoline companies also use methods before sale that result in the same change in the quality of their gasoline.

E．The gasoline storage tank on Haibei" s large enough to meet the needs of all of Haibei s different gasoline companies .

. Studies have shown that galaxies in many galaxy clusters are moving faster with respect to one another than they would if visible stars constituted all their mass. The studies suggest that the galaxies are moving under the gravitational influence of unseen mass in considerable quantity. Which of the following is an assumption underlying the passage above?

A．Measurements of the speed of moving galaxies are extremely unreliable.

B．The workings of gravitational forces are not particularly well understood.

C．The aggregate mass of visible stars in the galaxies mentioned above can be estimated with some confidence.

D．The general composition of unseen matter in the universe has been determined.

E．Without exception, the galaxies mentioned above move toward one another.

n those already sampled, our current estimate of reserves that exist underground must be multiplied by a factor of 10,000. From this we can conclude that we can meet the oil needs of the entire world for at least five centuries, even assuming that future consumption grows at an accelerating rate. To reach the stated conclusion, the author must assume which of the following?

A．It is possible to recover the oil contained in unexplored areas of the world.

B．The consumption rate for oil will not grow rapidly.

C．Oil will remain an important energy source for at least 500 years.

D．The world will achieve and maintain zero population growth.

E．New technology will make oil discovery and drilling more feasible than ever before.

r in a commercial to evoke the famous singer s well-known rendition of a certain song. As a result of the lawsuit, advertising firms will stop using imitators in commercials. Therefore, advertising costs will rise, since famous singers services cost more than those of their imitators. The conclusion above is based on which of the following assumptions?

A．Most people are unable to distinguish a famous singer"s rendition of a song from a good imitator" s rendition of the same song.

B．Commercials using famous singers are usually more effective than commercials using imitators of famous singers.

C．The original versions of some well-known songs are unavailable for use in commercials.

D．Advertising firms will continue to use imitators to mimic the physical mannerisms of famous singers.

E．The advertising industry will use well-known renditions of songs in commercials.