Option B, The warmer air contains more water vapor per unit of volume
Explanation:
The amount of water vapour contained in air depends on the temperature f air. A warm air has potential to hold more moisture as compared to cold air. Therefore when the temperature of air falls , its ability to hold moisture also falls.
An air with RH of 75% at 30 degree Celsius can hold 75% of moisture at this particular temperature. As the temperature increases, the ability of air to hold moisture also increases.
