Correct Answer: Diesel Engine

Solution : The correct answer is the Diesel engine.

Nitrogen dioxide is a gaseous air pollutant composed of nitrogen and oxygen. Nitrogen dioxide can form nitrates which can cause smog and reduce visibility. It is a major component of smog and it is a reddish-brown gas with a pungent odour. Diesel engines are considered one of the largest contributors to air pollution caused by exhaust emissions that lead to several health problems.