Which of the following cities suffers the most from air pollution?

The correct answer is Option (2) → Delhi

Delhi has a huge number of vehicles and many industries in and around the city. In winter, smoke and fog form urban smog over it. Of these four cities, Delhi has the poorest air quality, and it is among the most polluted cities in the world.

Note: This question is not from NCERT. NTA does this once in a while, but such questions are very few. Your NCERT is still enough.