What devices provide variable amounts of resistance to adjust output in a circuit?

The correct choice is indeed devices that provide variable amounts of resistance to adjust output in a circuit. A rheostat is a type of variable resistor specifically designed to control current flow by adjusting resistance. By varying the resistance, you can change the voltage drop across it, allowing you to fine-tune the current in a circuit to a desired level. This functionality is crucial in applications where precise control of electrical current is needed, such as in dimming lights or controlling the speed of a motor.

In contrast, resistors provide a fixed resistance and do not have the capability to adjust output within a circuit, which is essential for applications requiring variable control. Capacitors are used to store and release electric energy, and inductors store energy in a magnetic field; neither is typically used to adjust resistance in a circuit. Therefore, rheostats stand out as the appropriate choice for devices that can vary resistance to achieve specific output levels.