Final answer:
Country Z, with a central government that holds most of the power and is controlled by three top officials, is best described as having a unitary government and an oligarchy.
Step-by-step explanation:
In country Z, where the central government has the majority of the power and dictates the actions of smaller state governments, and is controlled by three top officials, the appropriate classification would be a unitary government system combined with an oligarchy. A unitary system is characterized by a centralized authority that holds the majority of the power, which is clearly present in country Z as the central government directs the actions of the local governments. Meanwhile, the governance by only three individuals points to an oligarchic structure, wherein a few people hold all the power. This setup contrasts with a federal system where power is more divided between the national and local levels, or with a more democratic system where power is typically dispersed among many more individuals or branches of government.