这两个逻辑题哪个大神帮我解释一下啊。。。。脑子有点糊涂不好使啊有木有！

kyang6

74. (29534-!-item-!-188;#058&004138)
In a certain wildlife park, park rangers are able to track the movements of many rhinoceroses because those animals wear radio collars.  When, as often happens, a collar slips off, it is put back on.  utting a collar on a rhinoceros involves immobilizing the animal by shooting it with a tranquilizer dart.  Female rhinoceroses that have been frequently recollared have significantly lower fertility rates than uncollared females.  robably, therefore, some substance in the tranquilizer inhibits fertility.
In evaluating the argument, it would be most useful to determine which of the following?
A. Whether there are more collared female rhinoceroses than uncollared female rhinoceroses in the park
B. How the tranquilizer that is used for immobilizing rhinoceroses differs, if at all, from tranquilizers used in working with other large mammals
C. How often park rangers need to use tranquilizer darts to immobilize rhinoceroses for reasons other than attaching radio collars
D. Whether male rhinoceroses in the wildlife park lose their collars any more often than the park’s female rhinoceroses do
E. Whether radio collars are the only practical means that park rangers have for tracking the movements of rhinoceroses in the park
75. (33198-!-item-!-188;#058&007254)
In the year following an eight-cent increase in the federal tax on a pack of cigarettes, sales of cigarettes fell ten percent.  In contrast, in the year prior to the tax increase, sales had fallen one percent.  The volume of cigarette sales is therefore strongly related to the after-tax price of a pack of cigarettes.  
Which of the following, if true, would most strengthen the argument above?
A. During the second year after the tax increase, cigarette sales increased by a significant amount.
B. The information available to consumers on the health risks of smoking remained largely unchanged in the period before and after the tax increase.
C. Most consumers were unaware that the tax on cigarettes was going to increase.
D. During the year following the cigarette tax increase, many consumers had less income, in inflation-adjusted dollars, than they had had in the previous year.
E. During the year after the tax increase, there was a greater variety of cigarettes on the market than there had been during the previous year.

yaozaizai

74,答案C。如果管理者使用tran就是为了radio这个原因，那么就可以支持文章的结论：recollar的犀牛比不collar的犀牛生育率低，recollar通常要用tran，不collar不用tran，所以有可能是tran导致生育率低。如果管理者因为其他原因用tran，不是为了radio，那么虽然recollar比不collar的生育率低，但是recollar和不collar的都没用到tran，那就不能说是tran这个导致的。