Answer: B.To prevent any one branch from becoming too powerful.
The separation of powers has been an intrinsic part of American government since the earliest days of the country. The basic outline comes from Federalist No. 47, by James Madison.
The Constitution of the United States divides the power of the state in three branches: executive, legislative and judicial. The objective of this separation is to ensure that the powers control and moderate each other (checks and balances) and that no branch becomes too powerful. Therefore, it prevents the state from falling into tyranny.
One example is the fact that the executive is considered the commander-in-chief of the Armed Forces, but only Congress has the power to declare war.
