What do both a fuse and circuit breaker do in a circuit?

A fuse and a circuit breaker serve the crucial function of protecting electrical circuits from damage due to excessive current. When the current flowing through the circuit exceeds a certain threshold, indicating an overload situation, both devices act to disconnect the circuit.

Fuses contain a metal strip that melts when too much current flows through, physically breaking the circuit. Circuit breakers, on the other hand, use a switching mechanism that can be reset after tripping. Both ensure safety by preventing overheating and potential fires, making option C the correct choice.

In contrast, the other options do not accurately describe the functions of fuses and circuit breakers. Decreasing voltage is not within their purpose, as they do not regulate voltage levels but rather interrupt current flow. Similarly, enhancing current flow contradicts their protective role, as both devices would cut the current during an overload rather than allow more flow. Lastly, while they may influence the overall current supply by interrupting it during an overload, their primary function is not to regulate current supply but to open the circuit during fault conditions.