Correct option is D
In an air washer, unsaturated air interacts with water droplets. This process can lead to:
Humidification: If the water temperature is higher than the dew point temperature (DPT) of the air, moisture is added to the air.
Dehumidification: If the water temperature is lower than the DPT of the air, moisture is removed from the air (condensation occurs).
Constant DPT: If the water temperature is maintained exactly at the DPT of the air, there is no net heat or mass transfer, and the DPT remains constant.
Thus, depending on the water temperature relative to the air's DPT, all three outcomes are possible.
