ANS:A - increases

The dew point of an unsaturated mixture of air and water vapor (at constant pressure and temperature) remains unchanged with an increase in absolute humidity. The dew point is the temperature at which air becomes saturated with water vapor, leading to condensation. In an unsaturated mixture of air and water vapor, where the air has not reached its saturation point, increasing the absolute humidity (the amount of water vapor present in the air) does not change the temperature at which saturation occurs. Therefore, the dew point remains constant under these conditions.