During the compression stroke, what is the status of the intake and exhaust valves?

During the compression stroke of an engine, the piston moves upwards in the cylinder, compressing the air-fuel mixture that has been drawn into the cylinder during the intake stroke. As the piston rises, it is critical for the engine's efficiency and performance that both the intake and exhaust valves are closed. This closure ensures that the compressed air-fuel mixture does not escape from the cylinder, allowing for optimal pressure to build up before ignition. The valves remain closed during this phase to maintain compression, which is essential for the engine to generate power effectively when the mixture is ignited.

The other options describe situations that would not occur during the compression stroke, such as having both valves open or having one valve open while the other is closed, which would interfere with the compression process.