The most widely used system of government in the world is this one, in which the national government is supreme, and states and/or provinces exercise only the powers that the national government chooses to give them
A. Unitary System
B. Federal System
C. Socialist System
D. Confederation

a. the unitary system

Explanation:

wikipedia defines the unitary system as:

"A unitary state is a state governed as a single power in which the central government is ultimately supreme. The central government may create administrative divisions. Such units exercise only the powers that the central government chooses to delegate."

well, paralell is parallel. i am providing links to .

hope this !

a series circuit is one with all the loads in a row. there is only one path for the electricity to flow. if this circuit was a string of light bulbs, and one blew out, the remaining bulbs would turn off.

unlike in series circuits, a charge in a parallel circuit encounters a single voltage drop during its path through the external circuit. the current through a given branch can be predicted using the ohm's law equation and the voltage drop across the resistor and the resistance of the resistor.

a parallel circuit has certain characteristics and basic rules: a parallel circuit has two or more paths for current to flow through. voltage is the same across each component of the parallel circuit.

the answer to your question is,

old stone age.

-mabel < 3