Which system in a vehicle is primarily responsible for reducing harmful emissions?

The exhaust system is primarily responsible for reducing harmful emissions in a vehicle. This system plays a vital role in the management of exhaust gases produced during combustion in the engine. It includes components such as the catalytic converter, muffler, and exhaust pipes, which work together to filter and convert harmful pollutants into less harmful substances before they are released into the atmosphere.

The catalytic converter, a key component of the exhaust system, performs a chemical reaction that transforms toxic gases like carbon monoxide, nitrogen oxides, and hydrocarbons into less harmful emissions such as carbon dioxide and water vapor. This process helps vehicles comply with environmental regulations and reduce their impact on air quality.

In contrast, while the fuel injection system is responsible for delivering fuel to the engine for efficient combustion, it does not directly manage emissions. The suspension system is concerned with the vehicle's handling and ride comfort, and the cooling system regulates engine temperature. None of these systems contribute to the management of exhaust gases in the way that the exhaust system does, making it the correct choice for addressing the reduction of harmful emissions.