What is the function of a spark plug in an engine?

The function of a spark plug in an engine is to send an electrical current that ignites the air-fuel mixture in the combustion chamber. When the engine's ignition system generates a high voltage, it travels through the spark plug to create a spark at its tip. This spark ignites the compressed air-fuel mixture, initiating the combustion process that powers the engine. The ignition must be precise, as the timing of the spark is crucial for the efficient operation of the engine.

The other functions mentioned in the options do not relate to the spark plug. Regulating fuel flow is managed by fuel injectors or carburetors, cooling down the engine is the role of the cooling system and radiator, while filtering exhaust gases is primarily handled by catalytic converters and other exhaust filtration systems. Understanding the spark plug's role helps in maintaining engine performance and troubleshooting issues related to ignition and combustion.