TO WHAT expedient, then, shall we finally resort, for maintaining in practice the necessary partition of power among the several departments, as laid down in the Constitution? The only answer that can be given is, that as all these exterior provisions are found to be inadequate, the defect must be supplied, by so contriving the interior structure of the government as that its several constituent parts may, by their mutual relations, be the means of keeping each other in their proper places."

Use the passage to answer the question.
What is the main purpose of this excerpt from The Federalist No. 51, and which of the following best illustrates it?

A.
to outline the powers of the executive branch; the president signs a treaty

B.
to outline the powers of the legislative branch; Congress changes the date of an election

C.
to outline the system of checks and balances among the three branches; the Supreme Court declares a law unconstitutional

D.
to outline the system of checks and balances among the three branches; the president announces that he will run for a third term

C. to outline the system of checks and balances among the three branches; the Supreme Court declares a law unconstitutional

This excerpt from The Federalist No. 51 discusses the necessity of maintaining the separation of powers among the different branches of government and the importance of checks and balances to ensure that each branch stays within its proper limits. The example of the Supreme Court declaring a law unconstitutional illustrates the concept of one branch checking the power of another to ensure that no single branch becomes too powerful.