What differentiates a remote-control circuit from other types of circuits?

A remote-control circuit is specifically designed to control another circuit, effectively allowing it to manage the operations of an electrical system from a distance. This feature is what primarily sets it apart from other types of circuits. The remote-control circuit typically sends signals or commands to another circuit, which can then perform functions such as turning devices on or off.

This ability to control another circuit without direct physical connection or manual operation underlines the unique functionality of remote-control circuits. For example, a remote-control light switch allows users to operate lighting from a distance, which exemplifies this characteristic of controlling another circuit.

The other options do not accurately reflect the defining features of a remote-control circuit. An independent power source, higher voltage, and the necessity for manual operation refer to different circuit functionalities that do not specifically distinguish remote-control circuits from others.