What is generally used to protect a system from overloading conditions?

The correct answer encompasses multiple protective measures—circuit breakers, fuses, and load shedding—each serving a distinct role in preventing system overloads.

Circuit breakers are automatic switches that interrupt the flow of electricity when they detect an overload or short circuit, effectively preventing damage to equipment and ensuring safety in the power system. They can be reset after an overload condition is resolved, allowing them to be reused.

Fuses, similarly, serve the purpose of protecting circuits by melting and thereby breaking the circuit when an overload occurs. They are simpler devices compared to circuit breakers; once a fuse is blown, it must be replaced to restore functionality.

Load shedding, on the other hand, is a strategy implemented to reduce demand on a system by turning off certain loads during peak usage times or under conditions that threaten system stability. This approach prevents overload by actively managing the load rather than just reacting to it once an overload condition arises.

Combining these methods provides a comprehensive approach to minimizing the risk of system overloading, thus "all of the above" is the most appropriate selection.