True or False: During the compression stroke, both valves are open.

During the compression stroke of an internal combustion engine, it is indeed true that both the intake valve and exhaust valve are closed. This closure is essential for the compression process, as it allows the piston to compress the air-fuel mixture within the cylinder effectively. If both valves were open during this stroke, the mixture would escape, resulting in a loss of pressure and power.

The timing of the valves is managed by the camshaft and the engine's design, ensuring that they only open and close at the appropriate times during the four strokes of the cycle: intake, compression, power, and exhaust. In most conventional engines, the intake valve closes before the compression stroke begins, and it remains closed until the compression stroke is completed, thereby maximizing efficiency and maintaining proper combustion dynamics.

Other choices such as "True" or "Depends on the engine type" would misrepresent the typical operation of standard four-stroke engines. While there are various engine configurations or designs that may alter valve timing, the basic principle that both valves are not open during the compression stroke holds true for most common engines.