Answer:
Increasing stirring rate and increasing temperature.
Step-by-step explanation:
1. Decreasing pressure doesn't do anything because pressure hardly has any affect on solid dissolving in liquid. Pressure only really matters when dissolving a gas into liquid.
2. Decreasing surface area is in the opposite idea. If you have less surface area, less of the solute is making contact with the solvent. The solvent has a harder time separating the solute. If there is more surface area, making more contact with the solvent, it'll be easier for the solvent. For example, sugar cube takes longer than 1/4 of that sugar cube.
3. Increasing the rate of stirring. Just like with collision theory, stirring helps with dissolving. The whatever liquid molecules are bouncing off the object and the walls. The motion both helps break down the solid solute and helps the solute make more contact with the solvent. Ex: watching instant coffee slowly descent into the water vs vigorously stirring powder into coffee.
4. Increasing temperature also makes the whatever liquid molecules bounce. Using one of the kinetic energy formulas, KE=3/2RT, T=temperature in kelvin, the higher the temperature, the higher the kinetic energy. The higher the kinetic energy, the faster the movement of the liquid molecules. The molecules will be making more contact with the solid solute, breaking it apart, surrounding the molecules, separating them.