Final answer:
The President's power to veto legislation passed by Congress is an example of checks and balances, as it allows the executive branch to check the legislative branch, while Congress can override the veto, showing balance between these branches.
Step-by-step explanation:
The principle of checks and balances is exemplified by the ability of different branches of the U.S. government to limit the powers of the other branches to prevent any one from becoming too powerful. Answer (a), "The President's power to veto legislation passed by Congress," is a classic example of this principle at work. Once Congress passes a bill, the President has the authority to veto it, checking the legislative power. However, Congress can override this veto with a two-third majority vote in both the House and the Senate, which is a check on the executive power and shows the balance of power between these branches.
Other examples of this system include the legislative branch's control over the judiciary, such as the Senate's power to confirm or reject the President's federal judge appointments, and the ability to rewrite legislation after a judicial ruling.