In the years since the city of London imposed strict air-pollution reg

E is wrong because we assume that the increase of bird species is related to ACTUAL increases in bird, rather than MORE people calling in with "sightings".

Suppose you have 100 birds - but instead of having 10 people calling in, now you have 50 people calling in.

Does that mean that there are more birds? nope. We still have 100. It just means that there are more people reporting them.

The answer must be A here - we know that pollution regulations on local industry in London have helped increase the number of birds. Presumably local industry then produces a significant amount of pollution, so the regulations may have helped to reduce pollution overall. Still, local industry does not need to be 'entirely' responsible for the pollution in order for regulations to help matters. Perhaps local industry only created 25% of the total pollution, but the regulations cut local industry pollution to zero; that would still have a significant impact on air quality.

If you bring outside opinions to the argument, E might be tempting - if you think reducing air pollution is good in and of itself, then E might not seem relevant. Still, if we analyze the argument -- Regulations in London led to more birds. Therefore these regulations are good and should be adopted by other cities. -- we see that the *only* reason the author gives for introducing regulations is to increase the number of birds - surely the author is assuming that's a good thing if he or she is proposing other cities introduce the same regulations.

The argument says, essentially, "London imposed air pollution laws. The number of birds went up. Therefore the rules should be applied everywhere."

It's an unstated assumption that having more birds is a good thing; it's the only justification for improving air quality that is provided. So D is one of the assumptions.

we should apply London's rules elsewhere assumes other cities are similar: C is an assumption.

The increased sightings of birds actually represents an increase in the number of birds is another assumption: E is also assumed.

Between B & A, i'll go with A
because

The argument does not assume that local industry is 'almost entirely' the source of air pollution. It only assumes that regulation on local industry will have a positive effect.

Conclusion : Similar air-pollution rules should be imposed in other major cities.
Premise : 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

Now Question asks for an option which is no where related to above as an assumption. SO lets drill down each option and strike it out.


(A) In most major cities, air-pollution problems are caused almost entirely by local industry.
-- This passage is concerned with local industry and this can be one probable assumption which fills the gap between premise and COnclusion. So this option is out .....Striked

(B) Air-pollution regulations on industry have a significant impact on the quality of the air.
---- Lets keep it aside for time being.

(C) The air-pollution problems of other major cities are basically similar to those once suffered by London.
--- London regulation outcome has triggered the conclusion. so its must as assumption. so Striked
(D) An increase in the number of bird species in and around a city is desirable.
---- This is the one result of regulation that triggered the implementation in other cities ....Striked
(E) The increased sightings of bird species in and around London reflect an actual increase in the number of species in the area.
---- This acts as an assumption. If when negated i.e.The increased sightings of bird species in and around London does not reflect an actual increase in the number of species in the area then there won't be any relevance between the premise and conclusion which will lead to fall of conclusion. So its Striked off

Now Option B is remaining ..." Air-pollution regulations on industry have a significant impact on the quality of the air " : This is the correct answer which doesn't act as any assumption for above conclusion to be drawn. Air quality doesn't quantify in the passage conclusion. Negating this i.e. Air-pollution regulations on industry does not have a significant impact on the quality of the air " doesn't affect the premise as the reason can be different for increase in species number and thus doesn't contradict the conclusion too. B doesn't affect the conclusion what so ever

OA is B

Remember that assumptions fill the gap that exists between the premise(s) and the conclusion. In this question, Premise 1 = London imposed strict air-pollution regs on local industry; Premise 2 = Bird species have increased as a result; and Conclusion = Similar air-pollution rules should be imposed in other major cities. Think about the gap between the conclusion and the premises. What do you have to believe in order for the conclusion (that the rules should be imposed on other cities) to be valid.

A-Do you have to believe that air-pollution is ALMOST ENTIRELY caused by local industry to believe that the helpful regs should be spread to other cities? No, This is an example of the GMAT using very extreme language to invalidate a choice. [In this case the extreme language invalidates an assumption and we are looking for the only non-assumption]
B-We have to believe that regulations impact the air quality or we wouldn't conclude that the regulations should be extended to other cities.
C-We would only conclude to take the same actions in these cities if the problems were similar.
D-We only make this conclusion if we want more birds!
E-We would only recommend (or conclude) to apply these regulations if the results are real/verifiable. If we are seeing more birds because we went to parks instead of looking out our 1st floor window, we can't conclude that these regulations should be spread to other cities. Only if the species actually did increase would we conclude that the regulations are worthy of replication.

A is the only non-assumption in the group (but E is a tempting option).

KW

I go with E too.

The reason that I didn't choose A is because the author believe that the air-pollution comes from the local industry. Therefore, the city of London set the regulation for local industry to control this problem. This action result in the increase of the number of bird species.

If such 99% of the pollution comes from other sources and the remaining 1% comes from the local industry, the regulation will not work. That's why I think A is an assumption as it shows that the local industry has an enormous impact on the air-pollution.

I'm not quite sure whether my point is correct. Please give me the advice

Yes, the decision between A and E can be tricky. Let's use negation to take a different view of these 2 choices. Negation is a bit of a challenge for A because it's difficult to form the "negative" version because it's not a binary, yes/no, situation but rather a degree of impact. To negate, we'll change the degree of impact from "almost entirely" to "only partly".

Here are the "negated" assumptions:
A-) In most major cities, air pollution is only PARTLY caused by local industry.
E-) The increased sightings of bird species in and around London DOES NOT reflect an actual increase in the number of species in the area.

When we negate true assumptions, the negated assumption will effectively destroy the conclusion. Which of the above most effectively destroys the conclusion? In A-, if the regulations on local industry (now only partly responsible for the pollution) still improve the number of species and we can still conclude that these regulations should be applied to other cities, therefore this is NOT a necessary assumption. In E-, if the regulations do not actually impact the number of species, we can no longer conclude that these regulations should be applied to other cities, therefore this IS a necessary assumption. A is the answer.

Does that help?

KW

Just curious... Is the argument not required to say something like

Similar air-pollution rules should be imposed in other major cities to increase the number of species.

BTW on a different note, you look like a carbon copy of Brandon Routh..

If we wanted to have a very structured argument with few holes (assumptions) we would explicitly state that these regulations should be imposed on other cities in order to increase the number of species. This is an EXCEPT question, so the GMAT purposely left this argument vague, or open to these assumptions.

Even if this weren't an except question the GMAT would be okay without restating the species premise. The structure of argument has cause/effect premises with a conclusion that recommends the cause be implemented in other areas implying that the same effect will be achieved. It's like me saying, I studied the GMAT while standing on my head and I got a great score, so you should study the GMAT while standing on your head. I don't have to restate the effect, because it's implied from the basic structure of my argument.

That's the first time I've been told I look like Brandon Routh. Maybe I should be Superman for Halloween.

KW

Pretty straight forward passage. Ignoring the negation rule for this assumption question may be the way to go.

We have strict air pollution regulations passed in the city of London. These regulations are passed on local industry.

Notice that we are not given the size or importance of this “local industry” in London. Also, we are not told how comprehensive these regulations are with respect to the percentage of local industry covered.

After these regulations are passed, the author observes the fact the number of sightings of bird species has risen around London.

On the basis of these two correlated events, the author makes the causal assumption and conclusion that similar regulations SHOULD be adopted in other major cities.


First, anytime an author makes a value judgement about what “should” be done, he or she is inherently assuming that the effect of the action is a net positive. In other words, the increase in the number of bird species is a good thing, in the author’s eyes. Otherwise, why else would the author feel that the same regulations should pass (with presumably the same effects) in other major cities?

(C) “The air pollution problems of the other major cities are similar to those in London.”

The author is making an assumption about that observed effect seen. The major assumption is that the regulations on local industry in London is what ultimately caused the number of bird species to rise. Because of this, the author claims that the same actions should be repeated in other cities.

In order for the same actions to be repeated in other cities and have a similar positive effect, there must be some similarities between these other major cities and London. Otherwise, the actions that worked in London might not work the same as they do in the other major cities.

(C) essentially highlights this assumption.

(D). As stated above, in order for the author to say that something “should” happen as a value judgment, he or she must be assuming that the result of the action is a good thing (unless we are told the author is an evil genius plotting to end the world).

To claim that the regulations should pass in the other major cities, the author must assume that the same effect of an increase in the number of bird populations will occur and that this effect is a positive, beneficial thing. Otherwise, the author wouldn’t have claimed that the regulations “should” be repeated elsewhere.

C and D must be assumptions they author is making.

(E) tells us that the increased sightings of birds in London actually reflects an increase in the number of bird populations.

The author is making a cause and effect assumption when he observes the fact of more sightings of birds in London. The author believes that the strict air pollution regulations passed on local industry are what caused the effect of an increase in the number of bird populations.

In order to claim that these regulations should be repeated in other major cities, the author must be assuming that the increase in the sightings of birds means that there are actually more birds. Otherwise, the cause and effect assumption the author makes about what happened in London wouldn’t make any sense. Further, it wouldn’t make any sense for the author to claim that the regulations should be repeated elsewhere.

The author, by making his value judgment, is assuming that the same effects will occur in other major cities when strict air pollution regulations are passed on local industry. The author believes that there will be a resulting increase in the number of bird populations. If the author does not assume that the bird sightings in London represent an actual increase in birds, then saying that other cities should adopt similar regulations lacks merit.

Can eliminate C, D, and E because they are require assumptions.

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

One could say that the author doesn’t need to assume anything about the regulations having an impact on the air. It could be that all the author sees is a correlation between imposed air pollution regulations and increased bird populations. Maybe this correlation will be repeated in the other major cities, regardless of the regulations’ effect on the air pollution.

However, without assuming the mechanism via which the bird populations are increasing (the regulations are actually impacting the air), it wouldn’t make sense for the author to believe that similar air pollution regulations should be enacted in other major cities. If the author doesn’t think the regulations are actually doing anything to help with the air, then he would have to assume that the act of just having the regulations in place leads to more birds. This isn’t that logical.

The only thing that is bothersome about (B) is the use of the word “significant”, but in the end (A) is a better choice.

(A) “In most major cities, air pollution problems are cause almost entirely by local industry.”

The key, major assumption made by the author is that the same cause and effect relationship he or she believes is happening in London will repeat itself when the regulations are applied to local industry in other major cities.

However, no where does it state that local industry in London makes up a majority of the air pollution problems in London. Still, the author observes the correlation of two events - the passage of the air pollution regulations and the increase in the number of bird populations - as a cause and effect relationship.

The author does not need to assume that the air pollution problems in these other cities come almost entirely from local industry. As long as the regulations have enough of an effect on the air pollution that is caused by local industry, then having the regulations stop that amount of pollution can very well be enough to lead to the same effect as was seen in London. It does not have to be the case the the local industry causes almost the ENTIRETY of the air pollution problems.

Furthermore, this is the kind of answer choice that can get you in trouble if you rely on the negation technique too much. If (A) were true, it would certainly strength the author’s claim that the same regulations should be passed elsewhere. It makes it more likely the regulations will have an effect on the air pollution problems, thus leading to an increase in the number of birds.

However, it is not essential the author assume this Fact in answer (A). Answer choices that strengthen an argument, but are not required assumptions, are often the hardest to eliminate

(A) is the only answer that is not a required assumption.

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