Explanation :
The amount of water vapor present in our surrounding is called the humidity.
We know that the pressure is equal to the force acting per unit area. Atmospheric pressure is defined as the force acting by air on a surface.
The relation between the atmospheric pressure and humidity is inverse i.e. if the air is more humid, the air pressure is low.
Hence, the correct option is (B) "Humid air is lighter, so it has lower pressure."
