For vehicles manufactured from 1984 and up, what is required in terms of catalytic converters?

For vehicles manufactured from 1984 and onward, catalytic converters are a required component due to federal emissions regulations implemented to reduce harmful vehicle emissions. The Clean Air Act, particularly amendments in the early 1980s, mandated that all cars and light trucks sold in the United States be equipped with catalytic converters to minimize the output of carbon monoxide, hydrocarbons, and nitrogen oxides.

This requirement applies to all vehicles meeting certain emission standards regardless of engine size or type. The presence of a catalytic converter plays a crucial role in the vehicle’s exhaust system, ensuring that it meets the environmental standards designed to protect air quality and public health. The technology helps in converting toxic gases produced during combustion into less harmful emissions before they exit the vehicle's exhaust system.

Thus, stating that catalytic converters are required on vehicles manufactured from 1984 onward aligns with these federal regulations, which is why this option is correct.