If pollution particles are high in a city and air is moist and cool what can increase?

Correct answer: Possibility of fog

Direct answer: D, the possibility of fog. Fog develops when moist air cools sufficiently for water vapour to condense into tiny droplets. Small particles in polluted urban air can provide surfaces, called condensation nuclei, on which water vapour may gather. If the air is already moist and cool, these conditions can make fog formation more likely, although pollution alone does not guarantee fog. D is correct because it connects moisture, cooling, and airborne particles with the chance of near-surface condensation. A is wrong because ocean salinity is not determined by city air particles in this situation. B is wrong because pollution and cool moist air do not cause a volcanic eruption. C is wrong because soil formation is a much slower process involving rock, organisms, climate, relief, and time, not immediate fog conditions. Memory cue: urban particles can help droplets form, but moisture and cooling are still necessary.