GMAT Critical Reasoning (CR) | Re: Weaken Revision: Recently in City X, developers have stopped

Please correct me if my logic is wrong, but the conclusion is "There must be fewer new residents moving to City X", and I think C does better job than other to weaken the conclusion (even there is a weakness in it). It doesn't matter if the ones who sold their old houses need new house or not or not, there are still many NEW RESIDENTs come to city X as they bought these old houses (The weakness of this Ans is of course there is possibility that the