Air Pollution in london

[subhasis8877]

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.

[asantosh1]

E

[subhasis8877]

OA is A

[thought]

This was pretty tough. At first read of the answers, I thought they all were assumed. On 2nd read, I got the official answer. Here's why.

My rephrasing of the argument:

Because London's strict local air-pollution regulations led to more bird species seen in and around London, similar air-pollution rules should be imposed in other major cities.

My approach was to NEGATE the answers and see if the argument still holds up. (If you negate an assumption the argument should not logically follow).

(B) If air-pollution regulations on industry DO NOT have a significant impact on the quality of the air then the premise falls apart. (London's regulations had no impact on air quality so it wasn't the regulations that led to more birds.)
(C) If the air-pollution problems of other major cities ARE NOT basically similar to those once suffered by London then you can't draw the argument's conclusion. (London is sooo different that it makes no sense to use London's regulations anywhere else.)
(D) If an increase in the number of bird species in and around a city is NOT desirable then you can't draw the argument's conclusion. (If more birds is not a good thing then why would you want to do something that leads to more birds.)
(E) If the increased sightings of bird species in and around London DO NOT reflect an actual increase in the number of species in the area then the premise falls apart. (More bird sightings don't mean more birds, so the regulation had no effect on the health of the bird population).

When I negated (A) at first, I thought that the argument fell apart.

If air pollution problems are not caused almost entirely by the local industry, why in the heck would you want to impose strict regulation just on local industry?

Reading this again (after eliminating the other answers), negating (A) still allows the argument to proceed.

In most major cities, air-pollution problems are NOT caused almost entirely by local industry but London's strict regulations (on the air-pollution that IS caused by local industry) led to more bird species seen in and around London, so it makes sense that similar air-pollution rules should be imposed in other major cities (even though non-local industries also contribute to pollution).

Just my thoughts. Does this help?

[subhasis8877]

Great explanation..Lesson is we should also look for the modifiers like"Entirely" in asnwer choices.

[kris77]

I like the explanation on A.