麻烦牛牛进来看看～一道题的疑问～－－0

       In the years since the city of London imposed strict air-pollution regulations on local industry, the number of bird species seen in and around London has increased dramatically. Similar air-pollution rules should be imposed in other major cities.

Each of the following is an assumption made in the argument above EXCEPT:

(A) In most major cities, air-pollution problems are caused almost entirely by local industry.

(B) Air-pollution regulations on industry have a significant impact on the quality of the air.

(C) The air-pollution problems of other major cities are basically similar to those once suffered by London.

(D) An increase in the number of bird species in and around a city is desirable.

(E) The increased sightings of bird species in and around London reflect an actual increase in the number of species in the area.

这道题是大全里的，答案是A，但是我不是很理解，麻烦各位指点一下迷津～谢谢啦～