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xixibie945

100.       

Lyme disease is caused by a bacterium transmitted to humans by deer ticks.  Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice.  However, certain other species on which the larvae feed do not harbor the bacterium.  If the population of these other species were increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.

Which of the following would it be most important to ascertain in evaluating the argument?

A. Whether populations of the other species on which deer tick larvae feed are found only in areas also inhabited by white-footed mice
B. Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on
C. Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice
D. Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed
E. Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans

我想问问这道题怎么用Heir解释啊？感觉B选项的解释：现在鹿的寄生虫的数量是否受到食物的限制？这个选项涉及到了一个“因”的特殊特点。如果寄生虫现在食物不足的话，那么当食物种类和数量增加的时候，只能活更多的寄生虫，而不会减少吃某种食物的幼虫的数量。 有点不太理解啊