一道GWD原题,jj,不懂,求助

1.       Some
species of Arctic birds are threatened by recent sharp increases in the
population of snow geese, which breed in the Arctic
and are displacing birds of less vigorous species.  Although snow geese are a popular quarry for
hunters in the southern regions where they winter, the hunting season ends if
and when hunting has reduced the population by five percent, according to
official estimates. Clearly, dropping this restriction would allow the other
species to recover.  Which of the
following, if true, most seriously undermines the argument?

(A)    Hunting
limits for snow geese were imposed many years ago in response to a sharp
decline in the population of snow geese.
            

(B)    It
has been many years since the restriction led to the hunting season for snow
geese being closed earlier than the scheduled date.
            

(C)    The
number of snow geese taken by hunters each year has grown every year for
several years.
            

(D)   As
their population has increased, snow geese have recolonized wintering grounds
that they had not used for several seasons.
            

(E)    In
the snow goose’s winter habitats, the goose faces no significant natural
predation.

题意:北极有鸟,名曰SG,近大肆繁衍,祸及他鸟,至众鸟流离失所,生灵涂碳!今悉SG每冬群移至南方避寒,届时猎人围而群捕之.然官府有令,SG之数减半成后,则猎期必止.遂有民鉴,若放开此令,则必可使受SG秧及之他鸟重得宁日. (哈哈,开个玩笑啦,意思能看懂吧)

It’s been many years since …. 就是自从什么以来已经很多年了,也就是很多年都没有这样了.B具体说的是,由于这个禁令(restriction)造成SG的捕猎期比预定时间(scheduled date)更早结束是很多年前才有的事,也就是这个捕杀SG是有个固定时间要结束的,可能是过完冬它们就回北方去了吧,具体题目好像没交代清楚.而这么多年以来,对SG的捕猎期是都是按照这个预定时间结束的,也就是在数量被捕杀超过5%以前,这些鸟就回去了,所以虽然有这个禁令,但是它却并没有发挥作用,没有减短对SG的捕猎期,那么,即使drop了这个restriction,也不会延长对SG的捕猎时间,不会造成更多的SG被捕杀.由于SG数量不会因drop restriction而进一步减少,所以其他species也不会recover,这就削弱了原题的结论了.