What environmental benefit do catalytic converters provide?

Catalytic converters serve a crucial role in reducing vehicle emissions by converting harmful pollutants produced during combustion into less harmful substances before they are released into the atmosphere. This process primarily targets three major pollutants: carbon monoxide, nitrogen oxides, and unburned hydrocarbons. By promoting chemical reactions within the converter, these harmful gases are transformed into nitrogen, carbon dioxide, and water vapor, which have a much lower environmental impact. This capability is vital for compliance with environmental regulations and contributes to cleaner air quality, making option C the correct choice.

The other options relate to aspects of engine performance or environmental impact but do not accurately represent the primary function of a catalytic converter. For instance, while fuel efficiency is important, it is not the direct role of a catalytic converter to enhance it. Similarly, noise pollution reduction and engine cooling are not functions of catalytic converters; they address different areas of vehicle operation and emissions management.