In the past ten years, there have been several improve- ments in mountain-climbing equipment. These improvements have made the sport both safer and more enjoyable for experienced climbers. Despite these improvements, however, the rate of mountain-climbing injuries has doubled in the past ten years.
If all of the statements above are true, which of the following, if true, best reconciles their apparent discrepancy?
Many climbers, lulled into a false sense of security, use the new equipment to attempt climbing feats of which they are not capable. Some mountain-climbing injuries are caused by unforeseeable weather conditions.. Mountain climbing, although a dangerous sport, does not normally result in injury to the experienced climber. In the past ten years there have been improvements in mountain-climbing techniques as well as in mountain- climbing equipment. Although the rate of mountain-climbing injuries has increased, the rate of mountain-climbing deaths has not changed.
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Scientists have rediscovered certain food crops, once commonly cultivated in the Americas, that contain more protein per pound than do current staple food crops such as rice and wheat. The scientists claim that cultivation of these crops could greatly benefit densely populated countries that have low per-person caloric intake and inadequate sources of protein.
Which of the following, if true, casts the most serious doubt on the claim reported above?
The average yield per acre of the rediscovered crops is substantially less than that. of current staple food crops. Many important food crops, such as tomatoes, originated in the Americas. Wheat yields more protein per pound than does rice. The rediscovered crops have more calories per pound than do current staple rood crops As few as 20 different food crops provide the bulk of the planet s food supply.
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A certain type of shrimp habitually hovers around superheated deep-sea geysers, near which the bacteria that form the shrimps diet can be found. Because the geysers emit a faint light, scientists have concluded that the shrimps light-sensitive dorsal patches were developed to locate the geysers and thereby find food.
Which of the following, if true, casts the most doubt on the scientists conclusion?
The light to which the shrimps are sensitive is not the sort of light that the geysers emit. The light given off by the geysers is too faint to be detected by the human eye. The heat inside a geyser s stream is sufficient to kill instantly any bacteria that move into it. Most other types of shrimp use eyes located at the end of eyestalks in order to see. In other types of shrimp. a heat-sensing organ has developed that could serve the same geyser-detecting purposes as the light-sensitive patches are said to serve.
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A school has four classroom suitable for art instruction. These classrooms are situated side by side along one straight hallway and are numbered consecutively 1 through 4. For the fall semester and also for the spring semester of an academic year, the school s four art teachers―Mr. Gilmore, Ms. Kramer, Ms. Lombardi, and Mr. Ramos―must each be assigned to these classrooms. one teacher to a room. The following restrictions on assignments must be observed:
No teacher can be assigned to the same classroom for the spring semester to. which that teacher is assigned for the
