Which feature of the u. s. government is an expression of the concept of federalism?
a. states have equal representation in the senate but proportional representation in the house of representatives.
b. the constitution is defined as the supreme law of the land.
c. the powers of the federal government are divided into three branches with a system of checks and balances.
d. certain powers are given to the federal government, while others are reserved for the states.

D. Certain powers are given to the federal government, while others are reserved for the states.

Explanation:

A political philosophy in which the political authority is divided between the centre and states is known as  Federalism. USA, Canada, Switzerland, Austria and European Union have federal form of government. In US federal system the power is shared between federal and state government. If there is disagreement between the federal and state government then the supreme court gives the final decision. Tenth Amendment deals with the powers of the states. Tenth amendment declares that the powers which are not given to the federal government are granted to the states.    

a phrase from a poem by ralph waldo emerson about the battle of lexington and concord. emerson's words read, “here once the embattled farmers stood / and fired the shot heard round the world.”