lsat test8/s2/q3

mzyzhu

Q3, 3. Citizen of Mooresville: Mooresville's current city council is having a ruinous effect on municipal finances. Since a majority of the incumbents are running for reelection, I am going to campaign against all these incumbents in the upcoming city council election. The only incumbent I will support and vote for is the one who represents my own neighborhood, because she has the experience necessary to ensure that our neighborhoods interests are served. If everyone in Mooresville would follow my example, we could substantially change the council's membership.

Assuming that each citizen of Mooresville is allowed to vote only for a city council representative from his or her own neighborhood, for the council's membership to be changed substantially, it must be true that

(A)    at least some other voters in Mooresville do not make the same exception for their own incumbent in the upcoming election

Why A is the right answer? What’s the meaning of same exception?