Which of the following is a type of variable resistor?

A rheostat is indeed a type of variable resistor. It is specifically designed to control current by adjusting resistance in a circuit. This adjustment allows for varying the voltage and current levels flowing through the circuit components, which is crucial in applications such as dimming lights, controlling motor speeds, or managing audio levels.

In contrast to the rheostat, capacitors, inductors, and transistors serve different functions in electrical circuits. Capacitors store energy in an electric field, inductors store energy in a magnetic field, and transistors act as switches or amplifiers. None of these components are variable resistors and they do not provide the same function of adjusting resistance to control current. This distinction makes the rheostat uniquely suited for applications where variable resistance is needed.