What system is designed to prevent one branch of government from becoming too powerful?

The correct choice is the system of checks and balances, which is a fundamental principle in the American government structure. This system is designed to ensure that no single branch of government—executive, legislative, or judicial—can dominate or abuse its power. Each branch has specific powers and responsibilities, and they are given mechanisms to monitor and limit each other's functions. For instance, the legislative branch can make laws, but the president has the power to veto those laws, and the judiciary can declare them unconstitutional.

While the separation of powers also plays a critical role by dividing responsibilities among the three branches, it is the checks and balances that actively work to maintain a balance of power. For instance, judicial review allows courts to assess the constitutionality of legislative acts, providing a check on legislative authority. However, checks and balances specifically refer to the interplay between branches that prevents any one from becoming too powerful or overstepping its bounds, making it the most accurate answer.

Federalism, which divides power between national and state governments, and judicial review, while important in their own contexts, do not directly address the internal balance among the three government branches in the same way checks and balances do.