What component is a part of a typical vehicle's charging system?

The voltage regulator is an essential component of a typical vehicle's charging system. Its primary function is to maintain the output voltage of the alternator within a specified range, ensuring that the electrical system of the vehicle operates efficiently. The voltage regulator helps prevent overcharging, which can damage the battery and electrical components, as well as undercharging, which can lead to insufficient power supply for the vehicle's electrical needs.

In contrast, other components listed do not belong to the charging system. The starter motor is involved in cranking the engine during startup but does not regulate or manage the charge of the battery. The fuel pump is responsible for delivering fuel to the engine, and the thermostat regulates the engine's temperature, neither of which are functions related to the vehicle's charging system. Therefore, the voltage regulator is the correct answer as it directly contributes to the proper function and management of the vehicle's electrical charging system.