Which of the following air pollutants helps in the formation of photochemical smog?

Oxides of nitrogen, reacting with hydrocarbons in sunlight, drive the formation of photochemical smog.

Carbon monoxide is a harmful pollutant but does not create photochemical smog directly.

Methane is a greenhouse gas and only a minor player in smog chemistry.

Oxides of sulphur cause acid rain and industrial smog, not photochemical smog.

Photochemical smog peaks on warm, sunny days in traffic-heavy cities.

Its key product is ground-level ozone, which irritates lungs and eyes.