If air temperature falls while vapour amount does not change, what happens in relation to dew point?

Correct answer: Air will approach dew point and condensation may occur

The dew point is the temperature at which air, if cooled without changing its water-vapour content, becomes saturated. When air temperature decreases while the actual amount of vapour remains constant, the same vapour represents a larger proportion of the air’s capacity to hold moisture. Relative humidity therefore rises, and the air moves closer to saturation and to its dew point. If cooling continues to the dew point, condensation may begin on surfaces or within the air.

The correct answer is option A. Cooling does not make vapour immediately disappear, and it cannot make relative humidity zero. The air moves toward the dew point, not away from it. At or below the appropriate saturation temperature, excess water vapour can change into liquid droplets, producing dew, fog, or clouds depending on the place and conditions. Thus, falling temperature with unchanged vapour amount makes condensation possible.