Which of the following controls the amount of fuel delivered to the engine?

The control that regulates the amount of fuel delivered to the engine is the throttle. The throttle is a mechanism that opens and closes to allow more or less air and fuel into the engine, directly impacting its power and speed. When you twist or press the throttle, it alters how much fuel and air mixture is sent to the engine, enabling it to accelerate or decelerate as needed.

The parking brake is used to secure the vehicle when it is stationary, which does not influence fuel delivery. The fuel supply valve is responsible for controlling fuel flow from the tank to the fuel system but does not manage the engine's intake of fuel and air while operating. The ignition switch is critical for starting the vehicle but has no role in regulating fuel delivery once the engine is running. Thus, the throttle is the essential control for determining engine fuel input.