Low air pressure is related with high humidity. This is due to molecules of water (H2O) replace molecules of nitrogen (N2) and molecules of oxygen (O2). Water molecules are lighter than nitrogen and oxygen molecules (molar mass of H2O is 18 g/mol, molar mass of O2 is 32 g/mol, and molar mass of N2 is 28). Then lower mass means lower weight which translates into lower pressure (remember air pressure is the weight of the air per unit of area). Then, the answer is the option B. cloudy, wet weather.
