A turbo charger does which of the following?

A turbocharger is a device designed to improve the efficiency and power output of an engine by utilizing the engine's exhaust gases to drive a turbine, which in turn forces more air into the engine's cylinders. This process increases the amount of oxygen available for combustion, allowing for a greater fuel-to-air mixture, which results in increased horsepower.

In this context, the correct answer reflects the main function of a turbocharger as it effectively blows compressed air (along with fuel) into the cylinders during the intake cycle. This action enhances the combustion process and ultimately boosts engine performance.

The other options suggest functions that are not accurate representations of what a turbocharger does. While cooling is an important aspect of engine operation, a turbocharger primarily focuses on air intake and efficiency rather than directly cooling the engine. Similarly, lubrication pertains to engine mechanics but is not a function of a turbocharger, and while enhanced exhaust flow can result from turbocharging, the key role of a turbocharger is to increase the intake of the air-fuel mixture, not just to push exhaust out faster.