请教NN一道GWD逻辑题，LD传染的加强

edi413

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 from feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. Therefore, if the population of these other species were increased, the number of ticks acquiring the bacterium and hence the number of people contracting Lyme disease would likely decline.

Which of the following, if true, most strengthens the argument?
1，Ticks do not suffer any adverse consequences from carrying the bacterium that causes Lyme disease in humans.
2，There are no known cases of a human’s contracting Lyme disease through contact with white-footed mice.
3，A deer tick feeds only once while in the larval stage.
4，A single host animal can be the source of bacterium for many tick larvae.
5，None of the other species on which deer tick larvae feed harbor other bacteria that ticks transmit to humans

答案选C，但是我觉得应该选B
因为不管狮子吃几次，但是不传染LD其他动物比例增加了狮子携带细菌的概率也会下降，所以C是无所谓的。比如说10个动物有有一个美腿耗子，那吃一次感染概率就是十分之一，但是增加到100个动物，概率就是百分之一，但是吃两次的话前者是百分之一，后者是万分之一，都减小了。
但是B就是排除他因了，假设人会从接触美腿耗子而感染LD，那么其他动物增加但是并不能导致人接触美腿耗子的概率减小呀？所以，B就排除了这种可能。
请NN帮帮忙看看，网上的答案都是C，我的立场在风雨中动摇。。。感谢

teddyteddy

題目: deer tick(larva)→w-f mice→human get LD
       deer tick(larva)→other →不會傳染給人                
答案B錯的原因 1.是否定了原文
                        2.是"there no known cases...",即使有,也無法得知其樣本是否具代表性;也就是說假設有 one case又如何? 怎知其不是特例? 因此也就無法排除他因

edi413

阁下说的也有很道理，文章第一句话就把LD的来源说的很明确，是不是这句话就算整个题目默认的公理？如果是的话当然不选B无可厚非，但是如此说来这道题岂不是没有正确答案了，因为我始终认为C更加不靠谱，原因还是同原帖所阐述。