Final answer:
The oligarchy was the form of government that lasted the longest in ancient Greece.
Step-by-step explanation:
In ancient Greece, the form of government that lasted the longest was A. oligarchy. Oligarchy is a form of government in which power is held by a small, elite group. This form of government allowed a small number of individuals to have control and influence over the city-state for an extended period of time. For example, Sparta was ruled by an oligarchy known as the Spartan Council of Elders.