Answer: A. Where the power of a government is located.
A federal government is one in which power is shared between the national government and the elected members of its subdivisions (provinces, states or territories). Therefore, there is an institutionalized division of authority between national and subnational governments.
On the other hand, a unitary government is one in which a single power (the central government) controls all the power of the government. Although the units can have responsibilities of their own, these are granted by the central government and can be broadened or narrowed as required.
Finally, a confederate government is one of very loose relationships among small political units. It is the other extreme of centralization, where a national government has very little power and most of the power rests with the individual government of those small units.