Which constitutional principle divides the federal government into three branches?
a. federalism
b. limited government
c. popular sovereignty
d. separation of powers

The correct answer is; the separation of powers. The separation of powers is the principle that divides the power into the executive, legislative and juidicial branches.

Federalism is the separation of powers between the local and the central government and limited government means that the government does not have absolute power. 

Ghana, first of the great medieval trading empires of western africa (fl. 7th–13th century). it was situated between the sahara and the headwaters of the sénégal and niger rivers, in an area that now comprises southeastern mauritania and part of mali.