Which is one of the four strokes in an internal combustion engine?

• A. Intake stroke
• B. Exhaust stroke
• C. Power stroke
• D. Compression stroke

Answer: (D)

The engine’s operating cycle contains four distinct strokes: intake, compression, power, and exhaust. During the compression stroke, the piston rises in the cylinder, closing the intake valve and reducing the space the gas occupies. This compression raises the air-fuel mixture’s pressure and temperature, making ignition—whether by a spark in gasoline engines or by high compression in diesel engines—more efficient when it enters the next stage. So the compression stroke is the step where the mixture is prepared for combustion, which is why it’s one of the four fundamental strokes.