A one-party system imposed by law with all other parties proscribed is
The correct answer is: B
Explanation
A one-party system imposed by law with all other parties proscribed is referred to as a "de jure one-party system." This means that the single-party rule is established by legal or official means, and the existence of other political parties is explicitly prohibited. This type of system is often associated with authoritarian or totalitarian regimes where political power is concentrated in a single party, and opposition parties are not allowed to operate legally.