What form of government is ruled by a single leader or party with absolute power?

The form of government ruled by a single leader or party with absolute power is a dictatorship. In a dictatorship, the governing authority often exercises total control over the political system and may suppress opposition, dissent, and individual freedoms. The leader or ruling party is not typically accountable to the public and may maintain power through coercion or propaganda.

In contrast, democracy emphasizes participation and representation from its citizens, where government officials are elected and policies are determined by majority rule. Monarchy involves rule by a king or queen, which can be absolute or constitutional, but generally includes a hereditary ruling class rather than a single, dictatorial leader. Oligarchy refers to governance by a small group of people, which can include multiple leaders or elites holding power rather than one individual. Thus, dictatorship specifically highlights the concentration of power in the hands of one ruler or party, making it the correct answer.