请教一道题

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.

为何答案是A啊？我选E。

请注意这句话：In the years since the city of London imposed strict air-pollution regulations on local industry。