Which example illustrates a situation where the balance of power is upheld?

The example of a President vetoing a law illustrates a situation where the balance of power is upheld due to the system of checks and balances inherent in the U.S. government. This system is designed to ensure that no single branch of government becomes too powerful or overreaches its authority. When the President vetoes legislation, it serves as a check on Congress's power to make laws. This action forces Congress to reconsider the proposed legislation and potentially amend it or provide sufficient justification for its passage, thereby maintaining a balance between the legislative and executive branches.

In contrast, the other examples don’t necessarily demonstrate this equilibrium. A governor passing a law does not involve the same kind of check on legislative power that the presidential veto does, as it typically reflects the authority granted to state executives. Similarly, a general issuing an order involves military authority rather than a political framework of checks and balances between branches of government. Lastly, a senator proposing a budget is an exercise of legislative function, but it does not explicitly show a balance of power because there are no checks being applied to it at that moment. Each branch has its own specific roles and powers, but the veto is a direct interaction designed to limit and balance those powers.