What Is a One-Party State

What is a one-party state?

A) It is a state in which the two major parties alternate in winning majorities, and only one party is in power at a time.
B) It is a state in which one party wins all or nearly all of the offices, and the second party receives only one-third of the popular vote.
C) It is a state in which only one party is allowed to contest the elections for all elected official positions.
D) It is a state in which only one party is allowed to contest the elections for the position of governor, but other parties are allowed to take part for other elected offices.
E) It is a country where there is one party at a federal level and another party at the state level.