Which one of the following is NOT part of the auto's starting system?

The starting system of an automobile is responsible for initiating the engine's operation when the driver turns the key or presses the start button. The primary components of this system work together to crank the engine and provide the necessary power for starting.

The starter solenoid is a crucial part of this system; it acts as a switch that allows current to flow from the battery to the starter motor when engaged. The battery supplies the electrical power needed to energize the starter motor and other components. The ignition switch is the mechanism that activates the starting system, allowing the electrical current to flow from the battery to the starter and other systems needed to start the engine.

In contrast, while spark plugs are essential for the engine's operation—particularly for igniting the fuel-air mixture in gasoline engines—they are not part of the starting system itself. Their role comes into play after the engine has started, as they facilitate combustion within the engine's cylinders. Therefore, identifying the spark plugs as not being part of the starting system directly correlates with the function of the starting system's components.