请教一题GWD，谢谢大家

11. GWD17-Q11:
            

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.

正确答案是B，不是很理解，谢谢！

看到太傻论坛上的一些解释，和大家共享：

A：没有说禁令本身是否有效

B：禁令已经有效实行多年了，但是SG的数量依然有大规模的上升，所以禁令和其他鸟恢复没有关系

C: 既可能削弱观点，也可能加强观点 （这个太微妙了，呵呵，大家可以仔细想想）

D: 不直接相关

E: E是非充分性地加强作者的观点

如果B改成限制没发生作用，即年年都是狩猎期正常结束，是不是也能对结论构成威胁？