How does smog form in cities?

Answer: Pollution reacts with sunlight

Pollution reacts with sunlight ✓ — Correct! Smog forms when vehicle and industrial emissions (nitrogen oxides, VOCs) react with sunlight, creating ground-level ozone and particulate matter. This is 'photochemical smog.' It's worse in sunny, high-traffic cities.

Clouds get trapped by buildings — Wrong. Smog isn't trapped clouds. It's pollution that reacts with sunlight to form harmful ozone and particulates. Geography can trap smog but buildings don't create it.

Cities produce natural fog — Wrong. Smog is air pollution, not natural fog (which is water vapor). Smog forms when emissions from vehicles and industry react with sunlight.