题目选项分析

Airport official: Local residents have been complaining that night flights into Plainsville airport disturb their sleep and should be sharply reduced in number. 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.

Which of the following is an assumption on which the airport argument depends?

【选项】People buying houses in Plainville all avoid buying houses near the airport if they can.