Critical Reasoning

richachampion wrote:Let's debate Why E can't be the correct answer.

Premise: Night flights have been coming into the airport for the past twenty years, a fact that local residents should have taken into account when buying their homes.
Conclusion: It is unreasonable for local residents to complain that night fights are disturbing their sleep.

Apply the NEGATION TEST.
When the correct answer choice is negated, the conclusion will be invalidated.
In other words, the negation of the correct answer choice will show that it is REASONABLE for local residents to complain about noise from night flights.

B, negated:
The residents who are complaining have been in their current homes for twenty years or longer.
Since night flights have been coming into airport only for the last 20 years, residents who have been in their current homes longer than 20 years could NOT have taken night flights into account when purchasing their homes, making it REASONABLE for them to complain about noise from night flights.
Since the negation of B invalidates the conclusion, B is the correct assumption: the answer choice that MUST BE TRUE for the conclusion to be valid.

The correct answer is B.

E, negated:
People buying houses in Plainville do not all avoid buying houses near the airport.
Here, at least one person does not avoid buying a house near the airport.
Since it remains true that local residents should have taken night flights into account when purchasing their homes, the negation of E does not make it reasonable for these residents to complain about noise from night flights.
Eliminate E.