What role does a turbocharger play in modifying air intake?

A turbocharger is an essential component in enhancing an engine's performance by modifying the air intake. It works by utilizing exhaust gases to spin a turbine, which in turn drives a compressor that draws in air and compresses it before it enters the engine's cylinders. This process increases the density of the incoming air, allowing more air—and therefore more fuel—to be injected into the cylinders. The result is a more powerful combustion process, leading to increased engine efficiency and power output.

In contrast, the other options don't accurately describe the function of a turbocharger. For instance, air purification, cooling, and pollutant removal are not the primary functions of a turbocharger, as these tasks involve other systems such as air filters, intercoolers, and catalytic converters. Thus, the role of a turbocharger in forcing pressurized air into the cylinders significantly contributes to the overall performance and efficiency of an engine.