What occurs during the intake stroke in a four-stroke engine?

During the intake stroke in a four-stroke engine, the piston moves down in the cylinder, creating a vacuum that allows the air and fuel mixture to be drawn into the combustion chamber. This process is essential for preparing the engine for the next phase of the cycle, where the mixture will be compressed and eventually ignited. The intake stroke is critical because it sets the stage for efficient combustion, ensuring that there is enough fuel and air for the engine to operate smoothly.

The other options describe different parts of the four-stroke cycle. Ignition occurs during the compression stroke, while expelling exhaust gases happens in the exhaust stroke. Additionally, the piston being at its highest point pertains to the end of the compression stroke, not the intake stroke. Understanding the distinct functions of each stroke is fundamental in comprehending how a four-stroke engine works effectively.