What component drives the entire unit of an air compressor?

The component that drives the entire unit of an air compressor is the electric motor. The electric motor provides the necessary power to operate the compressor, converting electrical energy into mechanical energy. This mechanical energy is then used to drive the compressor's pistons or rotors, which perform the actual work of compressing the air.

The electric motor's role is crucial because it initiates the entire compression cycle. Without it, the compressor would not function. It is designed to operate efficiently to meet the demands for compressed air, and its performance directly affects the output and reliability of the air compressor system.

While other components like the piston are essential for the compression process, they rely on the electric motor for their operation. Therefore, the electric motor's role as the driving force makes it the correct answer in this context.