Which of the following is NOT one of the four strokes of a four-stroke engine cycle?

In a four-stroke engine cycle, the operation is comprised of four distinct strokes: Intake, Compression, Power, and Exhaust. The correct answer identifies that "Ignition" is not explicitly listed as one of these strokes.

The intake stroke is where the engine draws in a mixture of air and fuel. The compression stroke follows, where this mixture is compressed to increase the efficiency of the combustion process. Next is the power stroke, during which the spark ignites the compressed mixture, leading to combustion and generating power for the engine. Finally, the exhaust stroke expels the burnt gases from the combustion chamber.

The confusion might arise around the term "ignition," as it is a crucial part of the combustion process, but it does not represent a separate stroke within the engine cycle. Instead, ignition occurs during the power stroke when the internal process of combustion takes place after compression. This distinction underscores why "Ignition" is not among the four fundamental strokes of the four-stroke cycle.