What functions do resistors serve in a circuit?

Resistors play a crucial role in electrical circuits by managing the flow of current, influencing the voltage levels, and dissipating energy in the form of heat. Their primary functions include dropping voltage, limiting the amount of current that can pass through the circuit, and developing heat due to the resistance to the flow of current.

When resistors are used in a circuit, they create a voltage drop according to Ohm's Law (V = I × R), which means that as current flows through the resistor, the voltage across it decreases. This is essential in controlling the voltage that reaches other components in the circuit, ensuring they operate within their specified limits.

Additionally, resistors limit current flow. In many applications, especially in series circuits, resistors are used to prevent excessive current that can overload and potentially damage sensitive components. The heat generated by resistors is a byproduct of their operation due to the energy conversion that takes place when current flows through them.

Thus, the correct choice encapsulates all these vital functions of resistors: they drop voltage, limit current, and develop heat, making them integral to the proper functioning of a wide array of electronic devices and circuits.