How does a diesel particulate filter (DPF) function?

A diesel particulate filter (DPF) is designed primarily to trap and remove soot and other particulate matter from the exhaust of diesel engines. The DPF functions by utilizing a porous filter medium that captures these solid particulates while allowing the exhaust gases to pass through. As the engine operates, the soot particles accumulate within the filter. Eventually, the DPF goes through a regeneration process where it reaches high temperatures, incinerating the trapped soot and reducing the particulate matter released into the atmosphere.

The other options do not accurately describe the function of a DPF. Reducing noise pollution pertains to sound dampening measures rather than particulate filtration. Increasing fuel efficiency is generally associated with engine tuning and optimization, not specifically with the function of a DPF. Cooling exhaust gases is done through components such as exhaust gas recirculation (EGR) systems and is unrelated to the filtration process of a DPF. Therefore, the correct answer perfectly describes the primary role of a diesel particulate filter in controlling emissions.