Which of the following is an example of the mechanical effect that is part of Duverger's Law? a. All six party systems in American history have been characterized by competition between two parties. b. In the House of Representatives in the Netherlands there are 10 parties because the legislature is elected by proportional representation. c. A voter in 2004 decides to vote for John Kerry rather than Ralph Nader because Nader is not competitive in the election but Kerry is. d. Although 1 percent of voters cast ballots for minor-party candidates in elections for the House of Representatives, no seats in the House go to a minor-party candidate.