Final answer:
The device that controls the volume of the fuel/air mixture to the cylinders is called the throttle body.
Step-by-step explanation:
The device that controls the volume of the fuel/air mixture to the cylinders in an internal combustion engine is called the throttle body. The throttle body is responsible for regulating the airflow into the engine, which in turn controls the fuel/air mixture. It is usually connected to the gas pedal and can be adjusted to increase or decrease the volume of the mixture entering the cylinders.