What type of engine utilizes a spark plug to ignite its fuel?

The spark ignition engine is designed specifically to use a spark plug to ignite the air-fuel mixture in the combustion chamber. This type of engine typically operates on a four-stroke cycle, where the spark plug creates a spark at the moment when the air-fuel mixture is compressed, triggering the combustion process. This leads to the expansion of gases that pushes the piston down, converting chemical energy into mechanical energy.

In contrast, the diesel engine operates under a different principle, utilizing compression ignition where fuel is injected into highly compressed air at the end of the compression stroke, causing it to ignite without a spark. Compression ignition engines follow a similar principle as diesel engines as they also rely on the compression process to ignite fuel. The rotary engine, known for its unique design and operation, does not utilize a traditional spark plug system, instead relying on its rotary mechanism for fuel combustion.

Thus, the correct response highlights the specific use of a spark plug in the ignition process of a spark ignition engine, which distinguishes it from the other types of engines mentioned.