What is federalism?
a. the division of governing powers between the national and state governments
b. the consolidating of national and state governments in times of need
c. the need for disagreement among all the branches of government
d. the cooperation between the federal branches of government

Federalism is a principle of separation of power, that between the national/federal/central government and between the local or state governments. This means that the states have a kind of autonomy: the right to decide over their own matters.

This means that the correct answer is:
A. the division of governing powers between the national and state governments

Multiplying frequency by period