Final answer:
An oligarchy is rule by a privileged few, different from monarchy or direct democracy, where a small elite group holds political power.
Step-by-step explanation:
Based on the information provided, an oligarchy is rule by D. a privileged few. An oligarchy is a form of government in which political power is held by a small, elite group. This group can be distinguished by various means, not necessarily hereditary in nature, such as military might, economic power, or religious status. The term 'oligarchy' comes with negative connotations often referring to a corrupt group making decisions that benefit themselves, and thus looks different from a monarchy where one hereditary ruler holds the power, or a direct democracy where citizens have direct influence over decisions.