In this chapter we present a methodology for proving in Zero Knowledge the validity of selecting a subset of a set belonging to predefined family of sets. We apply this methodology in electronic voting to provide for extended ballot options. Our proposed voting scheme supports multiple parties and the selection of a number of candidates from one and only one of these parties. We have implemented this system and provided measures of its computational and communication complexity. We show that the complexity is linear with respect to the total number of candidates and the number of parties participating in the election.