Which component reduces harmful emissions by converting them into less harmful substances?

The catalytic converter is a crucial component in modern vehicles designed specifically to reduce harmful emissions produced by the engine. It achieves this by using a chemical process that converts toxic gases such as carbon monoxide, hydrocarbons, and nitrogen oxides into less harmful substances like carbon dioxide and nitrogen. The converter typically contains precious metals such as platinum, palladium, and rhodium, which act as catalysts to facilitate these reactions at high temperatures.

In contrast to other components mentioned, such as the exhaust manifold, diesel particulate filter, and air intake system, the catalytic converter plays a unique and direct role in the chemical transformation of harmful pollutants. The exhaust manifold primarily collects and directs exhaust gases away from the engine rather than altering their composition. The diesel particulate filter focuses on trapping soot and particulates specifically from diesel engines, while the air intake system is designed to bring fresh air into the combustion chamber, contributing to efficient combustion but not directly involved in emissions reduction.

Thus, the catalytic converter stands out for its essential function in emission control, making it the correct choice for this question.