The party system refers to the complex network of relations between and among political parties. This network of relationships varies according to the number of parties, their size, power strategies and electoral system. The most commonly used criteria for classifying party systems is the number of parties competing for power. According to the classical classification of Duverger using the number criterion, there are three types of party systems: (1) One-party system, (2) Two-party system (3) Multi-party system. In the One-party system, a second party is not allowed except for one-party; there is only one- party in the system. One-party systems are divided into two groups. The authoritarian single parties that are not based on an inclusive ideology and the totalitarian One-parties based on a holistic ideology. The second group are communist and fascist parties that are mobilizing society through an ideology, aiming at a new type of human and society that conforms to this ideology. The best example of two-party systems is the US and UK. The two-party system is not the system with only two parties, but a system with two parties which have power potentials competing for political power. Around 90% of the total votes in almost every election is shared between the two parties. The ruling power changes in the hands of these two parties. Duverger states that a simple majority system only supports a two-party system. However, this is not a mechanical relationship. It should be noted that two-party systems work well in countries that have social consensus on the political regime. Multi-party systems are systems with more than two parties competing for power or having the power to influence power. It is divided into two as moderate and excessive multi-party systems. In the moderate multiparty system, parties tend to cluster around two centres. Power changes hands between these alliances that are formed to the right or left of the centre. According to Duverger, two-tiered majority systems support moderate multi-party systems. Excessive multiparty systems are not characterized by a large multiplicity of party numbers, but a multiplicity of political poles and the distance between them. The excessive multiparty system is seen in countries where there is a lack of consensus on the political regime and leads to instability of the government. Duverger believes that pure proportional representation systems support the multi-party system.

The correct answer is D