求助一道PREP逻辑题！！！！！

aglair萱

Lyme disease is caused by a bacterium transmitted to human 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 is most important to ascertain in evaluating the argument?

B whether the size of the deer tick population is currently limited by the availability of animals for tick's larval stage to feed on.

D whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer which infected deer tick's have fed.

我基本上就在B,D当中纠结着！！！就高人指点迷津！！！

shirleyon

prep的答案是B

B是说ticks是否因为食物少，数量被限制了。
引进other species作为它的食物，那数量就不受限制了。tick不管什么都会吃，吃感染细菌的数量也不会少。

D：幼虫时期不被感染，成虫时期是否会被感染。
原文讨论的是幼虫时期的事情，没有讨论成虫，所以无关

cdwayne

題目說ticks傳染L病的途徑是其幼蟲吸帶有細菌的mice的血(or體液)，但幼蟲也吸其他物種(不帶菌)的血，因此結論當這些不帶菌的幼蟲數量越多，越多幼蟲將不帶細菌，因此帶菌的ticks將減少。

(D) 若yes，則幼蟲雖不帶菌但成蟲還是有機會帶菌，將反駁原文結論。
     若no, 則相反，支持結論。

(B) 原文有些相對的比較意味，因此極端答案將不會有相反結果。