increase the production of ozone. decrease the production of smog. increase the emission of nitrogen. decrease the emission of carbon dioxide.
I gave my students this multiple choice question: Many cars are equipped with a catalytic converter, a device that helps remove hydrocarbons and oxides from car exhaust. As a result, this device helps to

Only one answer is correct among these 4 choices:
- increase the production of ozone.
- decrease the production of smog.
- increase the emission of nitrogen.
- decrease the emission of carbon dioxide.

Could you tell me which one is correct?

decrease the production of smog.