Which type of electoral system appears to contribute to the formation of a two-party system in any society?

A) single-member districts where, in order to win, the candidate must receive a plurality of votes
B) multi-member districts where, in order to win, the candidate must receive a minimum of 10 percent of votes
C) a multi-member district where, in order to win, the candidate must receive a majority of votes
D) a multi-member district that used the proportional representation method of selecting representatives for the legislative branch
E) all of the above

A