GWD17-Q11请教

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.

答案选b，不明白，首先restriction指的是什么？是说数量减少5%吗？如果根据b,restriction使hunting season提早结束，也就是说不到期限就打了5%，也就是说本可以打的更多，这不是加强吗？当然其他的选项也不对。。。。