What is the primary function of an alternator?

The primary function of an alternator is to convert mechanical energy into electrical energy. In automotive applications, the alternator is typically driven by the engine via a belt. As the engine runs, it rotates the alternator’s rotor, which creates a magnetic field. This magnetic field induces electrical current in the stator windings of the alternator, thereby generating electricity. This electricity is crucial for powering the vehicle's electrical systems and recharging the battery.

While storing electrical energy is a function associated with the battery, it is not the role of the alternator. Additionally, regulating fuel delivery and controlling engine temperature are functions related to other components in the vehicle, such as the fuel system and cooling system, respectively. Hence, the focus of the alternator's role is strictly on the conversion process, making option two the correct choice.