What distinguishes an actuator from a sensor?

An actuator is a device designed to control changes in the environment rather than simply monitoring them. It performs the action or movement needed to interact with the physical system by translating a control signal—typically from a control system or a sensor—into movement or action. For instance, in an automotive context, an actuator could be responsible for adjusting the throttle position, opening or closing valves, or steering a vehicle based on inputs received.

This functionality contrasts with the roles of sensors, which are tasked primarily with detecting and measuring environmental changes, translating those changes into electrical signals for data processing. While sensors might gather data about variables like pressure, temperature, or position, it is the actuators that take that data and perform necessary actions to adjust or control the system accordingly. Thus, the correct choice identifies the fundamental difference in purpose and operation between actuators and sensors.