Question

Which factor will have little effect on the solubility of saturated solutions?

Answer 1

A) The most important factor for solubility is temperature

We define the solubility of a substance in a solvent at a particular temperature

a) for solids the solubility increases with increase in temperature

b) for gas the solubility decreases with increase in temperature

So temperature will have huge effect on solubility of a saturated solution

B) the amount of extra time spent stirring the solution will hardly any effect or may have a very little effect. As stirring helps in solubility and if we have a saturated solution then it will not affect the solubility of the solution

C) The solubility is affected by the pressure on solvent

For gaseous solute the solubility is proportional to the pressure exerted on the solvent. More the pressure more the solubility.

D) the other solutes may affect the solubility as they may react with the solute or may interfere with the solute solvent interaction

Hence answer is "B"

Answer 2

I am absolutely sure that the factor which will have little effect on the solubility of saturated solutions is the amount of extra time spent stirring the solution. I choose this option because this point will not make a big difference whereas the rest of option can perform a great impact. 
Do hope you will find it useful!