Airport official: Local residents have been complaining that night fig

Although I marked it correctly as (B), I am not sure how (E) could be rejected.

Anyone?

A good test to check if the option we have picked is correct is the Negation test. Accordingly we would just have to negate the option and check if the negated version destroys the conclusion. If it does, then the reversed form is the best answer.
So let us try the negation with the options B and E.
In B we could read it as The residents who are complaining have not been in their current homes fewer than twenty years. If that is true then the conclusion would be destroyed because it ocnveys the meaning that they were probably longer than twenty years in their homes in which case they could not have taken into account the sound when buying the homes. The whole argument gets destroyed with the introduction of the not. .Hence this option is correct.
In Option E if we introduce the not it reads People buying houses in Planville will not avoid buying houses near the airport if they can. After negating the option the version does nothing to the conclusion. It says that people cant help themselves from buying houses near the airport. So is that the assumption? the assumption has to deal with the time period houses bought before 20 years andduring 20 years. The negation test when applied to E does nothing to the conclusion. Hence E is incorrect.

Initially got this wrong, but I see the correct answer now.

The premise is that residents in Plainville complain that the night flights are loud and disturb their sleep. The airport responds by saying home-buyers should have picked location more carefully and that the complaints are unreasonable.
What is the assumption?

A There are fewer night flights now than there were originally--irrelevant (maybe strengthens the argument)
B The residents who are complaining have been in their current homes fewer than twenty years--correct (the airport officials are assuming that people bought homes locally after the airport was built, but if we negate this we see that perhaps the airport was built after the homes were bought and thus, locals did not have have much choice in location of their homes)
C The residents who are complaining are ignoring the benefits they gain from he presence of the airport--irrelevant and out of scope (has nothing to do with the argument)
D The economic success of the airport depends entirely on the existence of the night flights--again irrelevant and out of scope (again has nothing to do with the argument)
E People buying houses in Plainville all avoid buying houses near the airport if they can--initially picked this, but it doesn't seem so relevant after understanding B (this would be more of a weakener, if anything) again irrelevant

ya.... since the people should have catered the problem which occured, since 20 years ago, therefore the houses must have been bought after that.....
answer is "b"....

Karishma, can u check if my approach is right. Chose B correctly and applied negation test.

(B) Residents have been living less than 20 years.

If residents lived more than 20 years, then their complaints were justifiable. Destroyed the official's argument (which stated that complaints are unreasonable as the people living in their homes should have thought about the problem at the time of buying the house).

(E) People avoid buying houses near the airport if they can.

If people willingly buy near airport, then it is their fault and they can't complain. This did not destroy the argument of the official.
It, I guess, strengthened it. So, (E) is wrong.

{I have a notion I am not applying this test correctly to (E). I got the question right and I am sure about it. But this worries me}

Thanks.

Actually, your analysis is absolutely correct. Check out my explanation for (E) given above. Essentially, the two are the same.

Thanks K !!! You're a life saver

Dear Experts,

Please throw some light on why option B is better than Option E.

Thanks for the Explanation Dmitry Farber

Negation technique would work best for this problem
mainly confusion is between choices B and E
option E provides us a effect that is occurring because of night flights whereas option B is a unstated premise that the residents have been living for less than 20 years.
If we negate option B then the conclusion falls apart and hence is the correct option

Negation technique would work best for this problem
mainly confusion is between choices B and E
option E provides us a effect that is occurring because of night flights whereas option B is a unstated premise that the residents have been living for less than 20 years.
If we negate option B then the conclusion falls apart and hence is the correct option

Thanks for the Input by the way whats the Conclusion here.

Why can't A be an assumption and what is the conclusion here?

akshaykotha The conclusion is "This complaint [that night flights are disturbing and should be reduced] is unreasonable." The only premise is that the flights have been going on for twenty years. The argument assumes that if the flights have been going on for 20 years, this provided ample time for people to choose another location. It also assumes that as long as people had this time, it's fine for the airport to run flights at night, and it's therefor unfair to complain. (This second assumption is not addressed in the answers.)

A isn't needed for the argument to succeed. The official is arguing that things have been the same for twenty years, not that things have gotten better. Even if the number of flights has not been reduced, the reasoning is the same.

DmitryFarber, your explanantion helps view the argument holistically rather than considering a specific point of view which was for me 'the number of flights'. Thank you!

Understanding the Argument -
Airport official: Local residents have been complaining that night fights at Plainsville airport disturb their sleep and should be sharply reduced in number. - Fact + Opinion
This complaint is completely unreasonable—there have been night flights coming into the airport from the very beginning, twenty years ago, and these residents should have taken that fact into account when buying their homes. - Conclusion + supporting premise.

Option Elimination - we need to find the missing premise or minimum condition or assumption that'll make the conclusion hold.

The key assumption here is that the people who are complaining have bought their houses within the last 20 years. If, for example, 100% of the people fall in the category who bought their houses 25 years back, the conclusion falls flat.

(A) There are fewer night flights now than there were originally - The scope of the argument is to find the missing premise for the conclusion that "The complaint is completely unreasonable because the very beginning, i.e., 20 years ago, these residents are aware and should have bought homes somewhere else." At best, this is out of scope.

(B) The residents who are complaining have been in their current homes fewer than twenty years - ok

(C) The residents who are complaining are ignoring the benefits they gain from the presence of the airport - Benefits are out of scope.

(D) The economic success of the airport depends entirely on the existence of the night flights - Economic success is out of scope which is to find the missing premise for the conclusion that "The complaint is completely unreasonable because the very beginning, i.e., 20 years ago, these residents are aware and should have bought homes somewhere else."

(E) People buying houses in Plainville all avoid buying houses near the airport if they can - Which means they don't have a choice. Even if they don't have a choice, they consciously choose this area, and now they can't complain for the same reasons (maybe the price because of the airport) because of which they bought the house there in the first place.