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GMATPrep question
Tigger bettles are such faster runners that they can capture virtually any nonflying insect. However, when running toward an insect, the bettles intermittently stop, and then, a moment later, resume their attack. Perhaps they cannot maintain their pace and must pause for a moment's rest; but an alternative hypothesis is that while running tiger bettles are unable to pocess the resulting rapidly changing visual information, and so quickly go blind and stop.
Which of the following, if discovered in experiments using artificially moved prey insect, would support one of the two hypotheses and undermine the other?
A. When a prey insect is moved directly toward a bettle that has been chasing it, the bettle immediately turns and runs away without its usual intermittent stopping.
B. In pursuing a moving insect, the beetles usually respond immediately to changes in insect's direction, and pause equally frequently whether the chase is up or down an incline.
C. The bettles maintain a fixed time interval between pauses, although when an insect that had been stationary begin to flee, the bettle increases its speed after its next pause.
D. If, when a bettle pause, it has not gained on the insect it is pursuing, the bettle generally ends its pursuit.
E. When an obstacle is suddenly introduced just in front of running beetles, the beetles sometimes stop immediately, but they never respond by running around the barrier.
The answer is C. But why?
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发表于 2006-9-23 16:15:00
