a) The pressure of a gas: As the pressure of a gas incrases, the solubility increases. AFFECTS
c) The temperature of the water: as the temperature of water incrases the solubility of a gas decreases. AFFECTS
d) Polarity of the gas molecules: water is a polar solvent, so it likes to dissolve polar molecules. The solubility of polar gases are greater that non-polar. AFFECTS.
b) The rate of stirring: stirring may affect the rate or speed at which a gas dissolves, but it doesn't affect the solubility of it. DOESN'T AFFECT
Answer: the factor that doesn't affect is the rate of stirring.