求大神，为什么选b求解释！

mike125615212

11. GWD17-Q11: B
Some species of Arctic birdsare threatened by recent sharp increases in the population of snow geese, whichbreed in the Arctic and are displacing birdsof less vigorous species.  Although snowgeese are a popular quarry for hunters in the southern regions where theywinter, the hunting season ends if and when hunting has reduced the populationby five percent, according to official estimates.  Clearly, dropping this restriction wouldallow the other species to recover.
Which of the following, iftrue, most seriously undermines the argument?

A.   Hunting limits for snow geese wereimposed many years ago in response to a sharp decline in the population of snowgeese.
B.   It has been many years sincethe restriction led to the hunting season for snow geese being closed earlierthan the scheduled date.
C.   The number of snow geese taken byhunters each year has grown every year for several years.
D.    ！Astheir population has increased, snow geese have recolonized wintering groundsthat they had not used for several seasons.
E.     Inthe snow goose’s winter habitats, the goose faces no significant naturalpredation.

christete

谢谢~

sdcar2010

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

In other words, what B says is that the 5% reduction in geese population due to hunting has never been reached for many years. Since B means hunters could not kill more than 5% of snow geese in a hunting season for many years, more than 5% reduction in geese population is unlikely to be reached even if such restriction is removed. In terms of grammar, It has been many years since (an event happened at a time in the past), simply means the time that event did happen was a long time ago.

Thus, answer B claims that the restriction set has no effect on the highest number of geese killed in a hunting season.  Therefore, removing the restiction would not lead to more killings of the geese and better chances for the other species to recover.  B weakens the argument.

If the hunting season was not closed early last year, that means the loss of the geese was below 5% of their population due to hunting.

Then if you remove the restiction of "only 5% of geese can be shot down each year," what kind of effect would you have on the geese population?

Nothing! Because the same hunters would show up and shot down the same number of geese - less than 5% of the total, just like what happened last year.