A system of government in which a single person or a group who governs has unlimited power is a

Step 1: Analyze the question The question asks for a system of government where a single person or a group holds unlimited (absolute) power.

Step 2: Explain the concepts

• Oligarchy: rule by a small group of people, often the wealthy or powerful. It is not defined by unlimited power, and it never refers to a single person.
• Republican: a system in which the head of state is elected and power is derived from the people. Power is limited by a constitution.
• Aristocracy: rule by a privileged, noble class, or by the "best" people, usually by birth.
• Autocracy: rule by one person (or sometimes a single ruling group) with absolute, unchecked power, not limited by laws, elections, or other institutions.

Step 3: Match the definition The key phrase is "unlimited power." The word autocracy comes from the Greek autos (self) and kratos (power or rule), meaning "self-rule" or rule by one with absolute authority. Examples include absolute monarchies, dictatorships, and military regimes without checks.

Oligarchy and aristocracy involve rule by a small group, but neither is defined by unlimited power. A republic is the opposite, because its power is limited.

Step 4: Answer The correct answer is D. autocracy.

Tip: Link auto = self, so autocracy means one self holding all power. Link oligo = few, so oligarchy means rule by a few. In JAMB Government, when you see "unlimited" or "absolute" power, think autocracy or dictatorship.