D) One party
If you look back in the day in The Soviet Union, Fascist Italy, and Nazi Germany, they were all forms of Dictatorships.
the Soviet Union had one party the Коммунистическая партия
Советского Союза (Communist party of the Soviet Union)
In Italy they had one party the Partito Nazionale Fascista (The National Fascist Party)
Lastly in Nazi Germany they had one party the Nationalsozialistische Deutsche Arbeiterparte (National Socialist German Workers Party)