What is the main purpose of a resistor in a circuit?

A resistor is primarily designed to limit or regulate the flow of electrical current in a circuit. It does this by providing a specific amount of resistance, which is a measure of how much the resistor opposes the flow of electric charge. This property allows resistors to control current levels effectively, helping to ensure that electronic components operate within their specified voltage and current ratings.

While resistors do convert some electrical energy into heat due to the resistance they provide (which relates to other options), their fundamental function is not to generate heat but to manage current flow. Resistors are not involved in storing energy like inductors, which create magnetic fields, nor do they generate voltage, which is the role of components like batteries and generators. Hence, the main purpose centers around current regulation, making the first statement the most accurate representation of a resistor's role in a circuit.