What is the correct path of air through a naturally aspirated engine?

In a naturally aspirated engine, the path of air begins at the air filter, which cleans the incoming air before it enters the engine. The air then moves into the throttle body, which regulates the amount of air entering the engine based on the driver's input on the accelerator pedal. From the throttle body, the air flows into the intake manifold, where it is distributed to the individual intake ports connected to each cylinder.

Each intake port leads directly to an intake valve for its respective cylinder. When the intake valve opens, the air enters the cylinder, allowing for the combustion process to occur. This sequence – from the throttle body to the intake manifold, then into the intake ports, through the intake valves, and finally into the cylinders – outlines the correct flow of air in a naturally aspirated engine.

This option accurately reflects the movement of air through the engine system, describing all the essential components involved in the intake process. Other options do not represent this correct sequence of air flow, as they misplace components or suggest that air can bypass critical stages in the intake process, leading to inaccuracies in how an internal combustion engine operates.