What is the primary purpose of an engine air filter?

The primary purpose of an engine air filter is to prevent dirt and debris from entering the intake system. This is crucial because any foreign particles can cause significant damage to the engine components, leading to reduced efficiency, increased wear, and potential failure. The air filter ensures that only clean air enters the combustion chamber, which is essential for optimal engine function and longevity. By filtering out contaminants, the air filter supports the overall health of the engine, enabling it to operate effectively and efficiently.

While factors such as fuel economy and engine performance can be indirectly influenced by the condition of the air filter, those are not its main functions. The air filter's primary role is strictly to maintain the cleanliness of the air entering the engine, making option C the correct answer.