What are the three essential components required to run an engine?

The three essential components required to run an engine are fuel, oxygen, and a spark ignition source. This combination is crucial for the internal combustion process that powers most vehicles.

Fuel, such as gasoline or diesel, provides the energy needed for combustion. Oxygen, which is obtained from the air, is necessary for the chemical reaction that occurs when the fuel is ignited. The spark ignition source, typically a spark plug in gasoline engines, initiates this combustion process by igniting the air-fuel mixture at the right moment in the engine's cycle.

The other options, while they mention components that are important for various aspects of engine function, do not encompass the core requirements necessary for the combustion process that drives an engine. For example, oil is essential for lubrication, but it is not directly involved in the combustion process, and while electricity is important for starting an engine and powering electronic components, it is not one of the fundamental components needed for combustion itself. Therefore, the correct answer highlights the specific elements required to start and maintain engine operation.