GMAT Critical Reasoning Test 39

Which of the following, if true and known by the ranchers, would best help explain the results of the study?

In tests for pironoma, a serious disease, a false positive result indicates that people have pironoma when, in fact, they do not; a false negative result indicates that people do not have pironoma when, in fact, they do. To detect pironoma most accurately, physicians should use the laboratory test that has the lowest proportion of false positive results. Which of the following, if true, gives the most support to the recommendation above?

In many corporations, employees are being replaced by automated equipment in order to save money. However, many workers who lose their jobs to automation will need government assistance to survive, and the same corporations that are laying people off will eventually pay for that assistance through increased taxes and unemployment insurance payments. The author is arguing that

According to the new office smoking regulations, only employees who have enclosed office may smoke at their desks. Virtually all employees with enclosed offices are at the professional level, and virtually all secretarial employees lack enclosed offices. Therefore, secretaries who smoke should be offered enclosed offices. Which of the following is an assumption that enables the conclusion above to be properly drawn?

Dental researchers recently discovered that tooth-brushes can become contaminated wth bacterial that cause pneumonia and strep throat. They found that contamination usually occurs after toothbrushes have been used for four weeks. For that reason, people should replace their toothbrushes at least once a month. Which of the following, if true, would most weaken the conclusion above?