选b: 1) 文章说只要when hunting has reduced the population by five percent,那么hunting season 就会结束,因此,不论是提前结束还是按时结束,都会产生一个相同的结果,就是population of the snow geese was reduced by five percent. 2)文章还有snow geese are a popular quarry for hunters 所以在hunting season 其他birds 也是会捕杀的。由 1,2 可得 hunting season 的提前结束,会给其他birds更多的时间来recover.所以restriction是有利的,也就weaken了结论。
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