Answer: Option (c) is the correct answer.
Step-by-step explanation:
Since, the substance added is a solid and particles of a solid are very closely held to each other because of strong intermolecular forces of attraction between them.
This makes them to have a definite shape and volume. Therefore, when pressure is applied on a solid then its particles will be least affected by it as they are already close to each other.
Whereas stirring, amount of surface area, and temperature will equally affect the rate of dissolution of the solid.
Hence, we can conclude that pressure is the factor that has least effect on the rate of solution of a solid in a liquid.