In response to viral infection, the immune systems of mice typically produce antibodies that destroy the virus by binding to proteins on its surface. Mice infected with the herpes virus generally develop keratitis, a degenerative disease affecting part of the eye. Since proteins on the surface of cells in this part of the eye closely resemble those on the herpes virus surface, scientists hypothesize that these cases of keratitis are caused by antibodies to the herpes virus.
Which of the following, if true, most helps to support the scientists’ reasoning?

The city of Workney, in raising bus fares from $1.00 to $1.25, proposed that 18 fare tokens be sold for $20.00 to alleviate the extra burden of the fare increase on the city’s poor people.Critics suggested alternatively that 9 fare tokens be sold for $10.00, because a $20.00 outlay would be prohibitive for poor riders.
The alternative proposal depends on which of the following assumptions?

A company has developed a new sensing device that, according to the company’s claims, detects weak,ultralow-frequency electromagnetic signals associated with a beating heart.These signals, which pass through almost any physical obstruction, are purportedly detected by the device even at significant distances. Therefore, if the company’s claims are true, their device will radically improve emergency teams’ ability to locate quickly people who are trapped within the wreckage of collapsed buildings.
Which of the following, if true, most strengthens the argument?

A prominent investor who holds a large stake in the Burton Tool Company has recently claimed that the company is mismanaged, citing as evidence the company’s failure to slow down production in response to a recent rise in its inventory of finished products. It is doubtful whether an investor’s sniping at management can ever be anything other than counterproductive, but in this case,it is clearly not justified. It is true that an increased inventory of finished products often indicates that production is outstripping demand, but in Burton’s case it indicates no such thing. Rather, the increase in inventory is entirely attributable to products that have already been assigned to orders received from customers.
In the argument given, the two boldfaced portions play which of the following roles?

Enforcement of local speed limits through police monitoring has proven unsuccessful in the town of Ardane. In many nearby towns, speed humps (raised areas of pavement placed across residential streets,about 300 feet apart) have reduced traffic speeds on residential streets by 20 to 25 percent. In order to reduce traffic speed and thereby enhance safety in residential neighborhoods, Ardane’s transportation commission plans to install multiple speed humps in those neighborhoods.
Which of the following, if true, identifies a potentially serious drawback to the plan for installing speed humps in Ardane?

Last year a record number of new manufacturing jobs were created. Will this year bring another record? Well, any new manufacturing job is created either within an existing company or by the start-up of a new company. With in existing firms, new jobs have been created this year at well below last year’s record pace. At the same time, there is considerable evidence that the number of new companies starting up will be no higher this year than it was last year and there is no reason to think that the new companies starting up this year will create more jobs per company than did last year’s start-ups. So clearly, the number of new jobs created this year will fall short of last year’s record.

In the argument given, the two portions in boldface play which of the following roles?

Boreal owls range over a much larger area than do other owls of similar size. Scientists have hypothesized that it is scarcity of prey that leads the owls to range so widely. This hypothesis would be hard to confirm directly, since it is not possible to produce a sufficiently accurate count of the populations of small mammals inhabiting the forests where boreal owls live. Careful study of owl behavior has, however, shown that boreal owls do range over larger areas when they live in regions where food of the sort eaten by small mammals is comparatively sparse. This indicates that the scientists’ hypothesis is not sheer speculation.
In the argument given, the two boldfaced portions play which of the following roles?

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 argue that Tropicorp’s actions do not serve even its own economic interest. However, the initial investment required for a successful rubber-tapping operation is larger than that needed for a cattle ranch; there is a shortage of workers employable in rubber-tapping operations;and taxes are higher on profits from rubber tapping than on profits from cattle ranching. 
Consequently, the environmentalists’ conclusion is probably wrong.
In the economist’s argument, the two boldface portions play which of the following roles?

Film Director: It is true that certain characters and plot twists in my newly released film The Big Heist are similar to characters and plot twists in Thieves, a movie that came out last year.Pointing to these similarities, the film studio that produced Thieves is now accusing me of taking ideas from that film. The accusation is clearly without merit. All production work on The Big Heist was actually completed months before Thieves was released.
Which of the following, if true, provides the strongest support for the director’s position?

A study compared a sample of Swedish people older than 75 who needed in-home assistance with a similar sample of Israeli people. The people in the two samples received both informal assistance,provided by family and friends, and formal assistance, professionally provided.Although Sweden and Israel have equally well-funded and comprehensive systems for providing formal assistance, the study found that the people in the Swedish sample received more formal assistance, on average, than those in the Israeli sample.
Which of the following, if true, does most to explain the difference that the study found?