Which engine part is responsible for allowing air and fuel into the engine while letting exhaust out?

The valves are a crucial component of an engine's operation, responsible for controlling the intake of air and fuel into the combustion chamber and the expulsion of exhaust gases after combustion. Specifically, there are typically two types of valves in a standard internal combustion engine: intake valves and exhaust valves. The intake valves open to allow the air and fuel mixture to enter the cylinder, while the exhaust valves open to release the exhaust gases once the combustion process is complete. This precise timing and operation of the valves is essential for efficient engine performance, making them central to the engine's ability to operate smoothly and effectively.

The other options refer to important components of the engine but do not serve the dual function of regulating airflow and exhaust. The piston is responsible for compressing the air-fuel mixture and converting combustion energy into mechanical motion. The crankshaft transfers that motion to the vehicle's drivetrain. Piston rings help to seal the combustion chamber and control oil consumption but do not manage the intake or exhaust processes.