In a(n) system, local and regional governments derive authority from the national government.

The answer to this question is "unitary". In a unitary system, local and regional governments derive authority from the regional government.In the state, there is a single power or a unity between them where all branches and agencies of the government excise only one power in their region that the central government chooses to be delegated. As a matter of fact, the majority in the world has this type of system.